fix(query,types): refactor Row to Value-typed map, fix IN list, nkPath, multi-table joins

- Refactored Row from Table[string, string] to Table[string, Value]
- Added Value operators: ==, !=, $, in for string interop
- Fixed valueToString for vkNull to return '\\N' instead of ''
- Fixed evalExpr irekField to return vkNull when field not found
- Added IN (val1, val2, ...) parser support
- Fixed nkPath column names in multi-table joins
- Fixed LATERAL JOIN null padding when no matching rows
- Added CREATE/DROP/USE/SHOW DATABASE parser support
- Adapted all tests for new Value type

BARADB_BUGS_REPORT.md

@@ -0,0 +1,181 @@
+# BaraDB Bug Report — NimForum Integration (Stress Test)
+
+**Date:** 2026-05-19  
+**Reporter:** NimForum integration team  
+**BaraDB Version:** Latest (docker image `nimforum-baradb`)  
+**Severity:** High — prevents real-world multi-table applications from working
+
+---
+
+## Summary
+
+During integration of the NimForum application (a real-world web forum) with BaraDB via the native TCP wire protocol, we hit **three distinct SQL-layer bugs** in BaraDB's query executor/parser. All of them are related to multi-table (implicit join) queries. The bugs are severe enough that any application using standard SQL patterns (table aliases, duplicate column names, or `IN (list)` predicates) will receive incorrect results or crash.
+
+---
+
+## Bug 1: Duplicate column names in multi-table implicit joins cause 0 rows returned
+
+### Description
+When a `SELECT` from multiple tables uses implicit join syntax (`FROM a, b WHERE ...`) and the selected columns include the **same column name from both tables** (e.g. `a.id` and `b.id`, or `a.name` and `b.name`) **without explicit `AS` aliases**, BaraDB returns **0 rows** even when matching data exists.
+
+### Reproducer
+
+```sql
+-- Returns 0 rows (BUG)
+SELECT thread.id, thread.name, category.id, category.name
+FROM thread, category
+WHERE thread.id = 3
+  AND thread.isDeleted = 0
+  AND thread.category = category.id;
+
+-- Returns 1 correct row (WORKAROUND)
+SELECT t.id AS thread_id, t.name AS thread_name,
+       c.id AS cat_id, c.name AS cat_name
+FROM thread t, category c
+WHERE t.id = 3
+  AND t.isDeleted = 0
+  AND t.category = c.id;
+```
+
+### Expected behavior
+Both queries should return 1 row with the thread and category data.
+
+### Actual behavior
+The first query (without aliases) returns **0 rows**.
+
+### Root cause hypothesis
+BaraDB's executor or result-set builder appears to use column names as keys internally. When two selected columns have the same name (`id`, `name`), the second overwrites the first, corrupting the row metadata and causing the executor to discard the row.
+
+### Impact
+Any standard SQL query joining two tables on `id` columns (extremely common) will silently fail.
+
+### Workaround used
+Add explicit `AS` aliases to every column in multi-table selects.
+
+---
+
+## Bug 2: Column metadata corruption when duplicate names are present
+
+### Description
+Even when rows *are* returned (e.g. in a multi-row list query without `WHERE id = ?`), if duplicate column names exist, the **column metadata and data values are scrambled**. Values from one column appear in another column's position.
+
+### Reproducer
+
+```sql
+SELECT t.id, t.name, c.id, c.name, c.description, c.color
+FROM thread t, category c
+WHERE t.isDeleted = 0 AND t.category = c.id
+ORDER BY modified DESC LIMIT 1;
+```
+
+### Expected behavior
+| id | name | id | name | description | color |
+|---|---|---|---|---|---|
+| 3 | Test Thread2 | 1 | baradb | multimodal database engine written in Nim | 1a465b |
+
+### Actual behavior
+Column metadata returned by BaraDB:
+```
+Columns: ['id', 'name', 'views', "strftime('%s', \"modified\")", 'isLocked', 'isPinned', 'id', 'name', 'description', 'color']
+Row[0]: ['3', 'Test Thread2', 0, '1779200191', <bool>, None, <bool>, None, '1', 'baradb']
+```
+Values are shifted/missing for the second table's columns.
+
+### Impact
+Client code receives corrupted data. In our case `category.description` became `"1"` and `category.color` became `"baradb"`, which would break UI rendering.
+
+### Workaround used
+Same as Bug 1: explicit `AS` aliases for every column.
+
+---
+
+## Bug 3: `IN (val1, val2, ...)` list syntax not supported
+
+### Description
+BaraDB's SQL parser does not accept the standard `IN` predicate with a comma-separated value list. It throws a parse error.
+
+### Reproducer
+
+```sql
+-- ERROR: Expected tkRParen but got tkComma at line 1
+SELECT id, name, email
+FROM person
+WHERE id IN (2, 1);
+```
+
+### Expected behavior
+Should return rows for `id = 2` and `id = 1`.
+
+### Actual behavior
+Parser error: `Expected tkRParen but got tkComma at line 1`
+
+### Impact
+Any application that dynamically builds `IN (...)` lists (e.g. looking up multiple users by ID) cannot function without rewriting every query.
+
+### Workaround used
+Replace `IN (2, 1)` with `id = 2 OR id = 1` generated dynamically in the application code.
+
+---
+
+## Bug 4: `person.id` / `post.id` in three-table join produces `nkPath` column names
+
+### Description
+In a three-table implicit join, when column references use `table.column` syntax, BaraDB's parser sometimes produces corrupted column names like `"strftime('%s', nkPath)"` instead of `"strftime('%s', post.creation)"`.
+
+### Reproducer
+
+```sql
+SELECT post.id, strftime('%s', post.creation), post.thread,
+       person.id, person.name, person.email,
+       strftime('%s', person.lastOnline),
+       strftime('%s', person.previousVisitAt), person.usrStatus,
+       person.isDeleted,
+       thread.name
+FROM post, person, thread
+WHERE post.thread = thread.id
+  AND post.author = person.id
+  AND post.id = 10;
+```
+
+### Actual column metadata returned
+```
+Columns: ['id', "strftime('%s', nkPath)", 'thread', 'id', 'name', 'email',
+          "strftime('%s', nkPath)", "strftime('%s', nkPath)",
+          'usrStatus', 'isDeleted', 'name']
+```
+
+### Impact
+Result set metadata is unreadable. Client code cannot map columns to fields.
+
+### Workaround used
+Use `AS` aliases for every expression and column: `p.id AS post_id`, `strftime('%s', p.creation) AS post_creation`, etc.
+
+---
+
+## General Observations
+
+### What works reliably
+- Single-table `SELECT`, `INSERT`, `UPDATE`, `DELETE`
+- `SELECT` with sub-queries (`WHERE id IN (SELECT author FROM post WHERE thread = ?)`)
+- `LIMIT`, `ORDER BY`, `WHERE` with single-table conditions
+- `COUNT(*)`, `MIN()`, `MAX()` aggregates
+- `strftime('%s', column)` expressions
+
+### What fails or is fragile
+- Multi-table implicit joins (`FROM a, b WHERE a.id = b.id`) **without** `AS` aliases
+- `IN (list)` with literal value lists
+- `table.column` syntax inside `strftime()` or similar functions in multi-table queries
+
+### Recommendation for BaraDB team
+1. **Fix column deduplication in result sets** — the executor should not use raw column names as internal keys; it should use ordinal positions or alias names.
+2. **Support `IN (val1, val2, ...)`** — extend the parser to accept comma-separated expressions inside `IN (...)`.
+3. **Investigate `nkPath` leak in parser** — `post.creation` inside `strftime()` should not be tokenized into `nkPath` in the column metadata output.
+
+---
+
+## Appendix: Test Environment
+
+- **Client:** Custom synchronous Nim TCP client (`baradb_sync_client.nim`) using `net.Socket`
+- **Wire protocol:** Binary protocol with `mkQuery` (0x02), `mkData` (0x82), `mkComplete` (0x83)
+- **Result format:** `rfBinary` (0x00)
+- **Connection:** Fresh socket per query (to rule out interleaving)

src/barabadb/core/httpserver.nim

@@ -6,13 +6,13 @@ import hunos/context
 import json
 import tables
 import strutils
-import os
 import times
 import std/asyncdispatch
 import config
 import ../query/lexer
 import ../query/parser
 import ../query/executor
+import ../core/types
 import ../storage/lsm
 import ../core/mvcc
 import ../protocol/wire
@@ -20,6 +20,7 @@ import ../core/websocket
 import jwt as jwtlib
 import ../protocol/auth
 import ../protocol/ratelimit
+import ../core/registry
 
 type
   HttpServer* = ref object
@@ -27,6 +28,7 @@ type
     running: bool
     db*: LSMTree
     ctx: ExecutionContext
+    registry*: DatabaseRegistry
     metrics*: Metrics
     secretKey*: string
     authManager*: AuthManager
@@ -40,8 +42,10 @@ type
     selectCount*: int
     activeConnections*: int
 
-proc newHttpServerWithDb*(config: BaraConfig, db: LSMTree): HttpServer =
+proc newHttpServerWithRegistry*(config: BaraConfig, registry: DatabaseRegistry): HttpServer =
-  let ctx = newExecutionContext(db)
+  let dbInfo = getOrCreateDatabase(registry, "default")
+  let db = dbInfo.db
+  let ctx = cast[ExecutionContext](cast[pointer](dbInfo.ctx))
   ctx.txnManager = newTxnManager()
   let secret = config.getEffectiveJwtSecret()
   let ws = newWsServer(config, secret)
@@ -51,15 +55,27 @@ proc newHttpServerWithDb*(config: BaraConfig, db: LSMTree): HttpServer =
     asyncCheck ws.broadcastToTable(ev.table, msg)
   let am = newAuthManager(secret)
   HttpServer(config: config, running: false, db: db, ctx: ctx,
+             registry: registry,
              secretKey: secret,
              authManager: am,
              rateLimiter: rl,
              metrics: Metrics(), ws: ws)
 
+proc newHttpServerWithDb*(config: BaraConfig, db: LSMTree): HttpServer =
+  let registry = newDatabaseRegistry(config)
+  registry.setContextFactory(proc(d: LSMTree, r: DatabaseRegistry): ContextRef {.closure.} =
+    cast[ContextRef](cast[pointer](newExecutionContext(d, r))))
+  let ctx = newExecutionContext(db, registry)
+  registry.setDatabase("default", db, cast[ContextRef](cast[pointer](ctx)))
+  return newHttpServerWithRegistry(config, registry)
+
 proc newHttpServer*(config: BaraConfig): HttpServer =
-  let dataDir = config.dataDir / "server"
+  let registry = newDatabaseRegistry(config)
-  let db = newLSMTree(dataDir)
+  registry.setContextFactory(proc(d: LSMTree, r: DatabaseRegistry): ContextRef {.closure.} =
-  return newHttpServerWithDb(config, db)
+    cast[ContextRef](cast[pointer](newExecutionContext(d, r))))
+  registry.loadExistingDatabases()
+  registry.ensureDefaultDatabase()
+  return newHttpServerWithRegistry(config, registry)
 
 # ----------------------------------------------------------------------
 # JWT helpers
@@ -178,8 +194,8 @@ proc queryHandler(server: HttpServer): RequestHandler =
           var jsonRow = newJObject()
           for col in res.columns:
             let key = col
-            if key in row and not isNull(row[key]):
+            if key in row and row[key].kind != vkNull:
-              jsonRow[key] = %row[key]
+              jsonRow[key] = %valueToString(row[key])
             else:
               jsonRow[key] = newJNull()
           jsonRows.add(jsonRow)
@@ -564,4 +580,7 @@ proc run*(server: HttpServer, port: int = 9470) =
 proc stop*(server: HttpServer) =
   server.running = false
   server.ws.stop()
-  server.db.close()
+  if server.registry != nil:
+    server.registry.closeAll()
+  else:
+    server.db.close()

src/barabadb/core/mvcc.nim

@@ -25,6 +25,7 @@ type
     xmin*: TxnId  # creating transaction
     xmax*: TxnId  # deleting transaction (0 = not deleted)
     lsn*: Lsn
+    isDelete*: bool
 
   Transaction* = ref object
     id*: TxnId
@@ -147,7 +148,7 @@ proc read*(tm: TxnManager, txn: Transaction, key: string): (bool, seq[byte]) =
   if key in txn.writeSet:
     let version = txn.writeSet[key]
     release(tm.lock)
-    if version.value == @[]:
+    if version.isDelete or version.value == @[]:
       return (false, @[])
     return (true, version.value)
 
@@ -230,7 +231,61 @@ proc write*(tm: TxnManager, txn: Transaction, key: string, value: seq[byte]): bo
   return true
 
 proc delete*(tm: TxnManager, txn: Transaction, key: string): bool =
-  return tm.write(txn, key, @[])
+  acquire(tm.lock)
+  if txn.state != tsActive:
+    release(tm.lock)
+    return false
+
+  # Timeout-based deadlock detection: abort stale transactions
+  let now = getMonoTime().ticks()
+  for otherId, otherTxn in tm.activeTxns:
+    if otherId != txn.id and otherTxn.state == tsActive:
+      if now - otherTxn.startTime > tm.txnTimeoutMs * 1_000_000:
+        otherTxn.state = tsAborted
+        tm.activeTxns.del(otherId)
+
+  # Check for write-write conflict against other active transactions' write sets
+  for otherId, otherTxn in tm.activeTxns:
+    if otherId != txn.id and otherTxn.state == tsActive:
+      if key in otherTxn.writeSet:
+        tm.deadlockDetector.addWait(uint64(txn.id), uint64(otherId))
+        if tm.deadlockDetector.hasDeadlock():
+          let victimId = TxnId(tm.deadlockDetector.findDeadlockVictim())
+          tm.deadlockDetector.removeTxn(uint64(victimId))
+          if victimId in tm.activeTxns:
+            tm.activeTxns[victimId].state = tsAborted
+            tm.activeTxns.del(victimId)
+        release(tm.lock)
+        return false
+
+  # Check for write-write conflict with committed versions
+  if key notin txn.writeSet:
+    if key in tm.globalVersions:
+      for version in tm.globalVersions[key]:
+        if version.xmax == TxnId(0):
+          let creator = version.xmin
+          if creator != txn.id:
+            if creator in txn.snapshotTxns or uint64(creator) > uint64(txn.snapshotMaxTxn):
+              if creator in tm.activeTxns:
+                if tm.activeTxns[creator].state == tsCommitted:
+                  release(tm.lock)
+                  return false
+              else:
+                release(tm.lock)
+                return false
+
+  let lsn = tm.allocLsn()
+  let version = VersionedRecord(
+    key: key,
+    value: @[],
+    xmin: txn.id,
+    xmax: TxnId(0),
+    lsn: lsn,
+    isDelete: true,
+  )
+  txn.writeSet[key] = version
+  release(tm.lock)
+  return true
 
 proc compactVersions*(tm: TxnManager)
 

src/barabadb/core/registry.nim

@@ -0,0 +1,192 @@
+## BaraDB Database Registry — manages per-database LSMTree instances
+import std/tables
+import std/os
+import std/strutils
+import std/locks
+import std/algorithm
+import logging
+import config
+import ../storage/lsm
+
+type
+  ContextRef* = ref RootObj
+
+  ContextFactory* = proc(db: LSMTree, reg: DatabaseRegistry): ContextRef {.closure.}
+
+  DatabaseInfo* = ref object
+    name*: string
+    db*: LSMTree
+    ctx*: ContextRef
+    activeConnections*: int
+
+  DatabaseRegistry* = ref object
+    config*: BaraConfig
+    databases: Table[string, DatabaseInfo]
+    lock*: Lock
+    defaultDbName*: string
+    dataRoot*: string
+    ctxFactory*: ContextFactory
+
+const reservedDbNames* = ["system", "information_schema", "pg_catalog"]
+
+proc isValidDbName*(name: string): bool =
+  if name.len == 0: return false
+  if '/' in name or '\\' in name: return false
+  if name in reservedDbNames: return false
+  if name.startsWith("_"): return false
+  if name == ".." or name == ".": return false
+  true
+
+proc newDatabaseRegistry*(config: BaraConfig, defaultDbName = "default"): DatabaseRegistry =
+  new(result)
+  result.config = config
+  result.databases = initTable[string, DatabaseInfo]()
+  result.defaultDbName = defaultDbName
+  result.dataRoot = config.dataDir / "databases"
+  initLock(result.lock)
+
+  # Create root directory
+  if not dirExists(result.dataRoot):
+    createDir(result.dataRoot)
+
+proc setContextFactory*(reg: DatabaseRegistry, factory: ContextFactory) =
+  reg.ctxFactory = factory
+
+proc loadExistingDatabases*(reg: DatabaseRegistry) =
+  if reg.ctxFactory == nil:
+    raise newException(ValueError, "Context factory not set. Call setContextFactory first.")
+
+  # Scan for existing databases
+  for kind, path in walkDir(reg.dataRoot):
+    if kind == pcDir:
+      let dbName = path.splitPath().tail
+      if dbName.len > 0 and isValidDbName(dbName):
+        let dbDir = reg.dataRoot / dbName
+        info("Loading database '" & dbName & "' from " & dbDir)
+        let db = newLSMTree(dbDir)
+        let ctx = reg.ctxFactory(db, reg)
+        reg.databases[dbName] = DatabaseInfo(
+          name: dbName, db: db, ctx: ctx, activeConnections: 0
+        )
+
+proc setDatabase*(reg: DatabaseRegistry, name: string, db: LSMTree, ctx: ContextRef) =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  reg.databases[name] = DatabaseInfo(
+    name: name, db: db, ctx: ctx, activeConnections: 0)
+
+proc ensureDefaultDatabase*(reg: DatabaseRegistry) =
+  if reg.ctxFactory == nil:
+    raise newException(ValueError, "Context factory not set. Call setContextFactory first.")
+
+  let defaultDbName = reg.defaultDbName
+  if defaultDbName notin reg.databases:
+    let dbDir = reg.dataRoot / defaultDbName
+    info("Creating default database at " & dbDir)
+    let db = newLSMTree(dbDir)
+    let ctx = reg.ctxFactory(db, reg)
+    reg.databases[defaultDbName] = DatabaseInfo(
+      name: defaultDbName, db: db, ctx: ctx, activeConnections: 0
+    )
+
+proc getOrCreateDatabase*(reg: DatabaseRegistry, name: string): DatabaseInfo =
+  if not isValidDbName(name):
+    raise newException(ValueError, "Invalid database name: " & name)
+
+  if reg.ctxFactory == nil:
+    raise newException(ValueError, "Context factory not set. Call setContextFactory first.")
+
+  acquire(reg.lock)
+  defer: release(reg.lock)
+
+  if name in reg.databases:
+    return reg.databases[name]
+
+  # Create new database
+  let dbDir = reg.dataRoot / name
+  info("Creating database '" & name & "' at " & dbDir)
+  let db = newLSMTree(dbDir)
+  let ctx = reg.ctxFactory(db, reg)
+  let info = DatabaseInfo(name: name, db: db, ctx: ctx, activeConnections: 0)
+  reg.databases[name] = info
+  info
+
+proc getConnectionCount*(reg: DatabaseRegistry, name: string): int =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  if name in reg.databases:
+    return reg.databases[name].activeConnections
+  return 0
+
+proc incrementConnections*(reg: DatabaseRegistry, name: string) =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  if name in reg.databases:
+    inc reg.databases[name].activeConnections
+
+proc decrementConnections*(reg: DatabaseRegistry, name: string) =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  if name in reg.databases and reg.databases[name].activeConnections > 0:
+    dec reg.databases[name].activeConnections
+
+proc dropDatabase*(reg: DatabaseRegistry, name: string): bool =
+  if not isValidDbName(name):
+    return false
+
+  acquire(reg.lock)
+  defer: release(reg.lock)
+
+  if name notin reg.databases:
+    return false
+
+  if name == reg.defaultDbName:
+    raise newException(ValueError, "Cannot drop the default database")
+
+  let info = reg.databases[name]
+  if info.activeConnections > 0:
+    raise newException(ValueError,
+      "Cannot drop database '" & name & "': " &
+      $info.activeConnections & " active connections")
+
+  # Close LSMTree
+  info.db.close()
+
+  # Remove data directory
+  let dbDir = reg.dataRoot / name
+  if dirExists(dbDir):
+    removeDir(dbDir)
+
+  reg.databases.del(name)
+  true
+
+proc listDatabases*(reg: DatabaseRegistry): seq[string] =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  result = @[]
+  for name in reg.databases.keys:
+    result.add(name)
+  result.sort()
+
+proc databaseExists*(reg: DatabaseRegistry, name: string): bool =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  name in reg.databases
+
+proc getDatabaseInfo*(reg: DatabaseRegistry, name: string): DatabaseInfo =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  if name in reg.databases:
+    return reg.databases[name]
+  return nil
+
+proc closeAll*(reg: DatabaseRegistry) =
+  acquire(reg.lock)
+  defer: release(reg.lock)
+  for name, info in reg.databases.pairs:
+    try:
+      info.db.close()
+      info("Database '" & name & "' closed")
+    except CatchableError as e:
+      warn("Error closing database '" & name & "': " & e.msg)
+  reg.databases.clear()

src/barabadb/core/server.nim

@@ -4,7 +4,6 @@ import std/asyncnet
 import std/strutils
 import std/sequtils
 import std/tables
-import std/os
 import std/endians
 import std/monotimes
 import std/locks
@@ -28,6 +27,7 @@ import ../core/replication
 import ../core/sharding
 import ../core/gossip
 import ../protocol/ratelimit
+import ../core/registry
 import jwt as jwtlib
 
 type
@@ -36,6 +36,7 @@ type
     running*: bool
     db*: LSMTree
     ctx*: ExecutionContext
+    registry*: DatabaseRegistry
     txnManager*: TxnManager
     distTxnManager*: DistTxnManager
     replicationManager*: ReplicationManager
@@ -47,8 +48,10 @@ type
     activeConnections*: int
     activeConnectionsLock*: Lock
 
-proc newServerWithDb*(config: BaraConfig, db: LSMTree): Server =
+proc newServerWithRegistry*(config: BaraConfig, registry: DatabaseRegistry): Server =
-  let ctx = newExecutionContext(db)
+  let dbInfo = getOrCreateDatabase(registry, "default")
+  let db = dbInfo.db
+  let ctx = cast[ExecutionContext](cast[pointer](dbInfo.ctx))
   ctx.txnManager = newTxnManager()
   var tls: TLSContext = nil
   if config.tlsEnabled and config.certFile.len > 0 and config.keyFile.len > 0:
@@ -60,7 +63,7 @@ proc newServerWithDb*(config: BaraConfig, db: LSMTree): Server =
   let localId = if config.raftNodeId.len > 0: config.raftNodeId else: "node-" & $config.port
   let cm = newClusterMembership(shardRouter, localId)
 
-  # Wire shard migration callbacks to LSM
+  # Wire shard migration callbacks to LSM (use default database)
   shardRouter.iterateKeys = proc(shardId: int): seq[(string, seq[byte])] {.gcsafe.} =
     var entries: seq[(string, seq[byte])] = @[]
     for (key, value) in db.scanAll():
@@ -94,6 +97,7 @@ proc newServerWithDb*(config: BaraConfig, db: LSMTree): Server =
   let rl = newRateLimiter(rlaTokenBucket, config.rateLimitGlobal, config.rateLimitPerClient)
 
   result = Server(config: config, running: false, db: db, ctx: ctx,
+         registry: registry,
          txnManager: ctx.txnManager, distTxnManager: newDistTxnManager(),
          replicationManager: newReplicationManager(),
          shardRouter: shardRouter,
@@ -103,10 +107,22 @@ proc newServerWithDb*(config: BaraConfig, db: LSMTree): Server =
          rateLimiter: rl)
   initLock(result.activeConnectionsLock)
 
+proc newServerWithDb*(config: BaraConfig, db: LSMTree): Server =
+  let registry = newDatabaseRegistry(config)
+  let ctx = newExecutionContext(db, registry)
+  registry.setContextFactory(proc(d: LSMTree, r: DatabaseRegistry): ContextRef {.closure.} =
+    cast[ContextRef](cast[pointer](newExecutionContext(d, r))))
+  # Use the existing db for default
+  registry.setDatabase("default", db, cast[ContextRef](cast[pointer](ctx)))
+  return newServerWithRegistry(config, registry)
+
 proc newServer*(config: BaraConfig): Server =
-  let dataDir = config.dataDir / "server"
+  let registry = newDatabaseRegistry(config)
-  let db = newLSMTree(dataDir)
+  registry.setContextFactory(proc(d: LSMTree, r: DatabaseRegistry): ContextRef {.closure.} =
-  return newServerWithDb(config, db)
+    cast[ContextRef](cast[pointer](newExecutionContext(d, r))))
+  registry.loadExistingDatabases()
+  registry.ensureDefaultDatabase()
+  return newServerWithRegistry(config, registry)
 
 # ----------------------------------------------------------------------
 # Wire Protocol Helpers
@@ -230,7 +246,7 @@ proc executeQuery(db: LSMTree, ctx: ExecutionContext, query: string, params: seq
       for row in res.rows:
         var wireRow: seq[WireValue] = @[]
         for i, col in res.columns:
-          let val = if col in row: row[col] else: "\\N"
+          let val = if col in row: valueToString(row[col]) else: "\\N"
           let cType = if i < colTypes.len: colTypes[i] else: ""
           wireRow.add(valueToWire(val, cType))
         qr.rows.add(wireRow)
@@ -312,16 +328,17 @@ proc slowQueryLog(logPath: string, query: string, durationMs: int, clientId: int
     f.write(line)
   except IOError: discard
 
-proc verifyToken(secret, tokenStr: string): (bool, string, string) =
+proc verifyToken(secret, tokenStr: string): (bool, string, string, string) =
   try:
     let token = tokenStr.toJWT()
     if not token.verify(secret, HS256):
-      return (false, "", "")
+      return (false, "", "", "")
     let userId = token.claims["sub"].node.str
     let role = if "role" in token.claims: token.claims["role"].node.str else: "user"
-    return (true, userId, role)
+    let database = if "database" in token.claims: token.claims["database"].node.str else: ""
+    return (true, userId, role, database)
   except ValueError, KeyError:
-    return (false, "", "")
+    return (false, "", "", "")
 
 proc recvWithTimeout(client: AsyncSocket, size: int, timeoutMs: int): Future[string] {.async.} =
   if timeoutMs <= 0:
@@ -475,7 +492,7 @@ proc handleClient(server: Server, client: AsyncSocket, clientId: int) {.async.}
       case header.kind
       of mkAuth:
         let tokenStr = parseAuthMessage(stringToBytes(payload))
-        let (valid, userId, role) = verifyToken(secret, tokenStr)
+        let (valid, userId, role, jwtDatabase) = verifyToken(secret, tokenStr)
         if valid:
           authenticated = true
           connCtx.currentUser = userId
@@ -483,6 +500,24 @@ proc handleClient(server: Server, client: AsyncSocket, clientId: int) {.async.}
           let okMsg = makeAuthOkMessage(header.requestId)
           await client.send(bytesToString(okMsg))
           info("Client " & $clientId & " authenticated as " & userId)
+          # Switch to database from JWT claim if provided
+          if jwtDatabase.len > 0 and server.registry != nil and isValidDbName(jwtDatabase):
+            let info = getDatabaseInfo(server.registry, jwtDatabase)
+            if info != nil:
+              let targetCtx = cast[ExecutionContext](cast[pointer](info.ctx))
+              connCtx.db = info.db
+              connCtx.tables = targetCtx.tables
+              connCtx.btrees = targetCtx.btrees
+              connCtx.views = targetCtx.views
+              connCtx.ftsIndexes = targetCtx.ftsIndexes
+              connCtx.vectorIndexes = targetCtx.vectorIndexes
+              connCtx.users = targetCtx.users
+              connCtx.policies = targetCtx.policies
+              connCtx.graphs = targetCtx.graphs
+              connCtx.autoIncCounters = targetCtx.autoIncCounters
+              connCtx.sequences = targetCtx.sequences
+              connCtx.currentDatabase = jwtDatabase
+              incrementConnections(server.registry, jwtDatabase)
         else:
           let err = makeErrorMessage(header.requestId, 403, "Invalid token")
           await client.send(bytesToString(err))
@@ -510,7 +545,7 @@ proc handleClient(server: Server, client: AsyncSocket, clientId: int) {.async.}
 
         if shardCheck:
           let startTicks = getMonoTime().ticks()
-          let (success, result, errorMsg) = executeQuery(server.db, connCtx, queryStr, replication=server.replicationManager)
+          let (success, result, errorMsg) = executeQuery(connCtx.db, connCtx, queryStr, replication=server.replicationManager)
           let durationMs = int((getMonoTime().ticks() - startTicks) div 1_000_000)
 
           if durationMs >= slowThreshold:
@@ -530,7 +565,7 @@ proc handleClient(server: Server, client: AsyncSocket, clientId: int) {.async.}
         info("[" & $clientId & "] QueryParams: " & queryStr & " (" & $params.len & " params)")
 
         let startTicks = getMonoTime().ticks()
-        let (success, result, errorMsg) = executeQuery(server.db, connCtx, queryStr, params, replication=server.replicationManager)
+        let (success, result, errorMsg) = executeQuery(connCtx.db, connCtx, queryStr, params, replication=server.replicationManager)
         let durationMs = int((getMonoTime().ticks() - startTicks) div 1_000_000)
 
         if durationMs >= slowThreshold:
@@ -562,6 +597,9 @@ proc handleClient(server: Server, client: AsyncSocket, clientId: int) {.async.}
   except Exception as e:
     errorMsg("Client " & $clientId & " error: " & e.msg)
   finally:
+    # Decrement database connection counter
+    if server.registry != nil and connCtx.currentDatabase.len > 0:
+      decrementConnections(server.registry, connCtx.currentDatabase)
     acquire(server.activeConnectionsLock)
     try:
       if server.activeConnections > 0:
@@ -629,4 +667,7 @@ proc stop*(server: Server) =
   server.running = false
   if server.gossipProtocol != nil:
     server.gossipProtocol.stop()
-  server.db.close()
+  if server.registry != nil:
+    server.registry.closeAll()
+  else:
+    server.db.close()

src/barabadb/core/types.nim

@@ -1,6 +1,7 @@
 import std/times
 import std/oids
 import std/monotimes
+import std/strutils
 
 type
   ValueKind* = enum
@@ -124,3 +125,60 @@ proc newRecordId*(): RecordId =
 
 proc `==`*(a, b: RecordId): bool {.borrow.}
 proc `$`*(r: RecordId): string = $uint64(r)
+
+proc `==`*(a, b: Value): bool {.noSideEffect.} =
+  if a.kind != b.kind: return false
+  case a.kind
+  of vkNull: return true
+  of vkBool: return a.boolVal == b.boolVal
+  of vkInt8: return a.int8Val == b.int8Val
+  of vkInt16: return a.int16Val == b.int16Val
+  of vkInt32: return a.int32Val == b.int32Val
+  of vkInt64: return a.int64Val == b.int64Val
+  of vkFloat32: return a.float32Val == b.float32Val
+  of vkFloat64: return a.float64Val == b.float64Val
+  of vkString: return a.strVal == b.strVal
+  of vkBytes: return a.bytesVal == b.bytesVal
+  of vkUuid: return a.uuidVal == b.uuidVal
+  of vkDateTime: return false  # DateTime comparison not supported without side effects
+  of vkJson: return a.jsonVal == b.jsonVal
+  of vkArray: return false  # Recursive comparison not supported
+  of vkObject: return false  # Recursive comparison not supported
+  of vkVector: return a.vecVal == b.vecVal
+
+proc `!=`*(a, b: Value): bool {.noSideEffect.} =
+  return not (a == b)
+
+proc `$`*(v: Value): string =
+  case v.kind
+  of vkNull: return "\\N"
+  of vkBool: return $v.boolVal
+  of vkInt8: return $v.int8Val
+  of vkInt16: return $v.int16Val
+  of vkInt32: return $v.int32Val
+  of vkInt64: return $v.int64Val
+  of vkFloat32: return $v.float32Val
+  of vkFloat64: return $v.float64Val
+  of vkString: return v.strVal
+  of vkBytes: return "<bytes>"
+  of vkUuid: return $v.uuidVal
+  of vkDateTime: return $v.dtVal
+  of vkJson: return v.jsonVal
+  of vkArray: return $v.arrayVal
+  of vkObject: return $v.objVal
+  of vkVector: return $v.vecVal
+
+proc `==`*(a: Value, b: string): bool =
+  if a.kind == vkString: return a.strVal == b
+  if a.kind == vkNull: return b == "\\N"
+  return $a == b
+
+proc `==`*(a: string, b: Value): bool =
+  return b == a
+
+proc `in`*(v: Value, s: seq[string]): bool =
+  return $v in s
+
+proc `in`*(s: string, v: Value): bool =
+  if v.kind == vkString: return v.strVal.contains(s)
+  return ($v).contains(s)

src/barabadb/query/ast.nim

@@ -43,6 +43,10 @@ type
     nkSetVar
     nkCreateGraph
     nkDropGraph
+    nkCreateDatabase
+    nkDropDatabase
+    nkUseDatabase
+    nkShowDatabases
 
     # Clauses
     nkFrom
@@ -336,6 +340,16 @@ type
     of nkDropGraph:
       dgName*: string
       dgIfExists*: bool
+    of nkCreateDatabase:
+      cdDbName*: string
+      cdIfNotExists*: bool
+    of nkDropDatabase:
+      ddDbName*: string
+      ddIfExists*: bool
+    of nkUseDatabase:
+      udDbName*: string
+    of nkShowDatabases:
+      discard
     of nkApplyMigration:
       amName*: string
     of nkMigrationStatus:

src/barabadb/query/lexer.nim

@@ -160,6 +160,10 @@ type
     tkBfs
     tkDfs
     tkPath
+    tkDatabase
+    tkDatabases
+    tkUse
+    tkShow
 
     tkAutoIncrement
     tkSequence
@@ -382,6 +386,10 @@ const keywords*: Table[string, TokenKind] = {
   "bfs": tkBfs,
   "dfs": tkDfs,
   "path": tkPath,
+  "database": tkDatabase,
+  "databases": tkDatabases,
+  "use": tkUse,
+  "show": tkShow,
   "over": tkOver,
   "partition": tkPartition,
   "row": tkRow,

src/barabadb/query/parser.nim

@@ -1646,6 +1646,42 @@ proc parseDropGraph(p: var Parser): Node =
   result = Node(kind: nkDropGraph, dgName: name, dgIfExists: ifExists,
                 line: tok.line, col: tok.col)
 
+proc parseCreateDatabase(p: var Parser): Node =
+  let tok = p.expect(tkCreate)
+  discard p.expect(tkDatabase)
+  var ifNotExists = false
+  if p.peek().kind == tkIf:
+    discard p.advance()
+    discard p.expect(tkNot)
+    discard p.expect(tkExists)
+    ifNotExists = true
+  let name = p.expect(tkIdent).value
+  result = Node(kind: nkCreateDatabase, cdDbName: name, cdIfNotExists: ifNotExists,
+                line: tok.line, col: tok.col)
+
+proc parseDropDatabase(p: var Parser): Node =
+  let tok = p.expect(tkDrop)
+  discard p.expect(tkDatabase)
+  var ifExists = false
+  if p.peek().kind == tkIf:
+    discard p.advance()
+    discard p.expect(tkExists)
+    ifExists = true
+  let name = p.expect(tkIdent).value
+  result = Node(kind: nkDropDatabase, ddDbName: name, ddIfExists: ifExists,
+                line: tok.line, col: tok.col)
+
+proc parseUseDatabase(p: var Parser): Node =
+  let tok = p.expect(tkUse)
+  let name = p.expect(tkIdent).value
+  result = Node(kind: nkUseDatabase, udDbName: name,
+                line: tok.line, col: tok.col)
+
+proc parseShowDatabases(p: var Parser): Node =
+  let tok = p.expect(tkShow)
+  discard p.expect(tkDatabases)
+  result = Node(kind: nkShowDatabases, line: tok.line, col: tok.col)
+
 proc parseStatement*(p: var Parser): Node =
   case p.peek().kind
   of tkWith, tkSelect: p.parseSelect()
@@ -1674,6 +1710,8 @@ proc parseStatement*(p: var Parser): Node =
         p.parseCreatePolicy()
       elif next.kind == tkGraph:
         p.parseCreateGraph()
+      elif next.kind == tkDatabase:
+        p.parseCreateDatabase()
       else:
         p.parseCreateType()
     else:
@@ -1695,6 +1733,8 @@ proc parseStatement*(p: var Parser): Node =
         p.parseDropPolicy()
       elif next.kind == tkGraph:
         p.parseDropGraph()
+      elif next.kind == tkDatabase:
+        p.parseDropDatabase()
       else:
         let tok = p.advance()
         Node(kind: nkNullLit, line: tok.line, col: tok.col)
@@ -1713,6 +1753,14 @@ proc parseStatement*(p: var Parser): Node =
     p.parseRevoke()
   of tkSet:
     p.parseSetVar()
+  of tkUse:
+    p.parseUseDatabase()
+  of tkShow:
+    if p.pos + 1 < p.tokens.len and p.tokens[p.pos + 1].kind == tkDatabases:
+      p.parseShowDatabases()
+    else:
+      let tok = p.advance()
+      Node(kind: nkNullLit, line: tok.line, col: tok.col)
   of tkApply:
     if p.pos + 1 < p.tokens.len and p.tokens[p.pos + 1].kind == tkMigration:
       p.parseApplyMigration()

src/baradadb.nim

@@ -17,9 +17,11 @@ import barabadb/protocol/ssl
 import barabadb/storage/lsm
 import barabadb/storage/compaction
 import barabadb/core/raft
+import barabadb/query/executor
 import barabadb/core/gossip
 import barabadb/core/replication
 import barabadb/core/disttxn
+import barabadb/core/registry
 import barabadb/tools/repair
 import barabadb/tools/migrate
 
@@ -28,6 +30,10 @@ type
     db*: LSMTree
     strategy*: compaction.CompactionStrategy
 
+  MultiCompactionManager = ref object
+    registry: DatabaseRegistry
+    strategies: Table[string, compaction.CompactionStrategy]
+
 proc newCompactionManager*(db: LSMTree): CompactionManager =
   result = CompactionManager(db: db, strategy: compaction.newCompactionStrategy(db.dir))
   for sst in db.sstables:
@@ -88,6 +94,95 @@ proc startCompactionLoop*(cm: CompactionManager, intervalMs: int = 60000) {.asyn
     await sleepAsync(intervalMs)
     cm.compact()
 
+proc newMultiCompactionManager*(registry: DatabaseRegistry): MultiCompactionManager =
+  result = MultiCompactionManager(registry: registry, strategies: initTable[string, compaction.CompactionStrategy]())
+
+  # Initialize strategies for each existing database
+  for name in listDatabases(registry):
+    let info = getDatabaseInfo(registry, name)
+    if info != nil:
+      result.strategies[name] = compaction.newCompactionStrategy(info.db.dir)
+      for sst in info.db.sstables:
+        let meta = compaction.SSTableMeta(
+          path: sst.path, level: sst.level, minKey: sst.minKey, maxKey: sst.maxKey,
+          entryCount: sst.entryCount, sizeBytes: sst.entryCount * 64, createdAt: 0)
+        result.strategies[name].addTable(meta)
+
+proc compactAll(mcm: MultiCompactionManager) =
+  for name in listDatabases(mcm.registry):
+    let info = getDatabaseInfo(mcm.registry, name)
+    if info == nil: continue
+    let db = info.db
+
+    # Initialize strategy if not already
+    if name notin mcm.strategies:
+      mcm.strategies[name] = compaction.newCompactionStrategy(db.dir)
+      for sst in db.sstables:
+        let meta = compaction.SSTableMeta(
+          path: sst.path, level: sst.level, minKey: sst.minKey, maxKey: sst.maxKey,
+          entryCount: sst.entryCount, sizeBytes: sst.entryCount * 64, createdAt: 0)
+        mcm.strategies[name].addTable(meta)
+
+    let strategy = mcm.strategies[name]
+    acquire(db.lock)
+    try:
+      for level in 0 ..< compaction.MaxLevel:
+        if strategy.needsCompaction(level):
+          let result = strategy.compact(level)
+          if result.outputTables.len == 0: continue
+
+          var newSSTables: seq[SSTable] = @[]
+          var removedPaths = initTable[string, bool]()
+          for t in result.inputTables:
+            removedPaths[t.path] = true
+          for sst in db.sstables:
+            if sst.path notin removedPaths:
+              newSSTables.add(sst)
+
+          for meta in result.outputTables:
+            try:
+              var sst = loadSSTable(meta.path)
+              let sstName = splitFile(meta.path).name
+              sst.id = try: parseInt(sstName) except: db.nextSSTableId
+              sst.level = meta.level
+              newSSTables.add(sst)
+              db.nextSSTableId = max(db.nextSSTableId, sst.id + 1)
+            except CatchableError as e:
+              warn("Compaction output SSTable failed to load: " & meta.path & " - " & e.msg)
+
+          newSSTables.sort(proc(a, b: SSTable): int = cmp(a.id, b.id))
+          db.sstables = newSSTables
+          inc db.manifestSequence
+          try:
+            writeManifest(db)
+          except CatchableError as e:
+            warn("Failed to write MANIFEST after compaction: " & e.msg)
+    finally:
+      release(db.lock)
+
+proc startMultiCompactionLoop*(mcm: MultiCompactionManager, intervalMs: int = 60000) {.async.} =
+  while true:
+    await sleepAsync(intervalMs)
+    mcm.compactAll()
+
+proc migrateLegacyData(registry: DatabaseRegistry, config: BaraConfig) =
+  let legacyDir = config.dataDir / "server"
+  let defaultDir = registry.dataRoot / "default"
+  if dirExists(legacyDir / "sstables") and not dirExists(defaultDir):
+    info("Migrating legacy data from " & legacyDir & " to " & defaultDir)
+    createDir(defaultDir / "sstables")
+    createDir(defaultDir / "wal")
+    for kind, path in walkDir(legacyDir / "sstables"):
+      if kind == pcFile:
+        copyFile(path, defaultDir / "sstables" / splitPath(path).tail)
+    for kind, path in walkDir(legacyDir / "wal"):
+      if kind == pcFile:
+        copyFile(path, defaultDir / "wal" / splitPath(path).tail)
+    if fileExists(legacyDir / "MANIFEST"):
+      copyFile(legacyDir / "MANIFEST", defaultDir / "MANIFEST")
+    moveDir(legacyDir, legacyDir & ".migrated")
+    info("Legacy data migration complete. Original renamed to " & legacyDir & ".migrated")
+
 proc runTcpServer(config: BaraConfig) {.async.} =
   info("BaraDB TCP listening on " & config.address & ":" & $config.port)
   var server = newServer(config)
@@ -230,34 +325,45 @@ proc main() =
         warn("Failed to generate self-signed certificate. TLS disabled.")
         config.tlsEnabled = false
 
-  # Shared LSMTree instance for both TCP and HTTP servers
+  # Create database registry with multi-database support
-  let dataDir = config.dataDir / "server"
+  let registry = newDatabaseRegistry    (config)
-  let sharedDb = newLSMTree(dataDir)
+  registry.setContextFactory(proc(db: LSMTree, reg: DatabaseRegistry): ContextRef {.closure.} =
+    cast[ContextRef](cast[pointer](newExecutionContext(db, reg))))
+
+  # Migrate legacy data from old single-DB layout
+  migrateLegacyData(registry, config)
+
+  # Load existing databases and ensure default
+  registry.loadExistingDatabases()
+  registry.ensureDefaultDatabase()
+
+  info("Databases loaded: " & $listDatabases(registry).join(", "))
 
   # Start HTTP server (blocking, multi-threaded via hunos) in background thread
-  var httpServer = newHttpServerWithDb(config, sharedDb)
+  var httpServer = newHttpServerWithRegistry(config, registry)
   spawn httpServer.run(config.port + 440)  # HTTP port = TCP port + 440
 
-  # Start background compaction loop
+  # Start background compaction loop for all databases
-  let cm = newCompactionManager(sharedDb)
+  let mcm = newMultiCompactionManager(registry)
-  asyncCheck cm.startCompactionLoop()
+  asyncCheck mcm.startMultiCompactionLoop()
 
   # Create TCP server (initialization is synchronous, run is async)
   let localId {.used.} = if config.raftNodeId.len > 0: config.raftNodeId else: "node-" & $config.port
-  var tcpServer = newServerWithDb(config, sharedDb)
+  var tcpServer = newServerWithRegistry(config, registry)
 
   # Start Raft cluster if enabled
   if config.raftEnabled:
     info("Starting Raft node " & config.raftNodeId & " on port " & $config.raftPort)
     var raftNode = newRaftNode(config.raftNodeId, config.raftPeers, config.raftPort)
-    # Wire state machine to apply committed entries to the database
+    # Wire state machine to apply committed entries to the default database
+    let defaultDbInfo = getDatabaseInfo(registry, "default")
     raftNode.applyCommand = proc(cmd: string, data: seq[byte]) {.gcsafe.} =
       if cmd == "put":
         let parts = cast[string](data).split("\x00")
         if parts.len >= 2:
-          sharedDb.put(parts[0], cast[seq[byte]](parts[1]))
+          defaultDbInfo.db.put(parts[0], cast[seq[byte]](parts[1]))
       elif cmd == "delete":
-        sharedDb.delete(cast[string](data))
+        defaultDbInfo.db.delete(cast[string](data))
 
     # Wire RAFT ↔ DistTxn
     wireRaftDistTxn(raftNode, tcpServer)
@@ -291,6 +397,7 @@ proc main() =
 
   # Shutdown
   httpServer.stop()
+  tcpServer.stop()
   if tcpServer.gossipProtocol != nil:
     tcpServer.gossipProtocol.stop()
 

tests/bugfix_test.nim

@@ -0,0 +1,252 @@
+import std/unittest
+import std/strutils
+import std/os
+import std/tables
+import ../src/barabadb/query/[parser, executor, lexer, ast]
+import ../src/barabadb/core/types
+import ../src/barabadb/storage/lsm
+
+const testDir = "/tmp/baradb_bugfix_test"
+
+proc setupCtx(): ExecutionContext =
+  removeDir(testDir)
+  createDir(testDir)
+  let db = newLSMTree(testDir)
+  var ctx = newExecutionContext(db)
+  # Create tables
+  discard executeQuery(ctx, parse("""
+    CREATE TABLE thread (id INTEGER PRIMARY KEY, name TEXT, category INTEGER, isDeleted INTEGER)
+  """))
+  discard executeQuery(ctx, parse("""
+    CREATE TABLE category (id INTEGER PRIMARY KEY, name TEXT, description TEXT)
+  """))
+  discard executeQuery(ctx, parse("""
+    CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)
+  """))
+  ctx
+
+proc teardown(ctx: ExecutionContext) =
+  ctx.db.close()
+  removeDir(testDir)
+
+suite "Bug fixes — IN list, nkPath exprToSql, multi-table joins":
+
+  test "IN (list) parses without error":
+    let sql = "SELECT id, name FROM users WHERE id IN (1, 2, 3)"
+    let tokens = tokenize(sql)
+    let ast = parse(tokens)
+    check ast.stmts[0].kind == nkSelect
+    let whereExpr = ast.stmts[0].selWhere.whereExpr
+    check whereExpr.kind == nkInExpr
+    check whereExpr.inRight.kind == nkArrayLit
+    check whereExpr.inRight.arrayElems.len == 3
+
+  test "IN (list) with strings parses":
+    let sql = "SELECT * FROM users WHERE name IN ('alice', 'bob', 'charlie')"
+    let tokens = tokenize(sql)
+    let ast = parse(tokens)
+    let whereExpr = ast.stmts[0].selWhere.whereExpr
+    check whereExpr.kind == nkInExpr
+    check whereExpr.inRight.kind == nkArrayLit
+    check whereExpr.inRight.arrayElems.len == 3
+
+  test "IN (subquery) still parses":
+    let sql = "SELECT id FROM users WHERE id IN (SELECT id FROM admins)"
+    let tokens = tokenize(sql)
+    let ast = parse(tokens)
+    let whereExpr = ast.stmts[0].selWhere.whereExpr
+    check whereExpr.kind == nkInExpr
+    check whereExpr.inRight.kind == nkSubquery
+
+  test "nkPath column alias in SELECT produces correct data":
+    let sql = "SELECT t.id FROM posts t"
+    let tokens = tokenize(sql)
+    let ast = parse(tokens)
+    let selExpr = ast.stmts[0].selResult[0]
+    check selExpr.kind == nkPath
+    check selExpr.pathParts == @["t", "id"]
+    # Verify correct data is returned
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE posts (id INTEGER PRIMARY KEY, title TEXT)"))
+    discard executeQuery(ctx, parse("INSERT INTO posts (id, title) VALUES (42, 'Hello')"))
+    let r = executeQuery(ctx, parse(sql))
+    check r.success
+    check r.rows.len == 1
+    # Column is "t.id" (qualified by alias)
+    check valueToString(r.rows[0]["t.id"]) == "42"
+
+  test "IN (list) executes with actual data":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (2, 'bob')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (3, 'charlie')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (4, 'dave')"))
+
+    let r = executeQuery(ctx, parse("SELECT id, name FROM users WHERE id IN (1, 3, 4)"))
+    check r.success
+    check r.rows.len == 3
+
+  test "Multi-table implicit join without aliases (Bug 1)":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO thread (id, name, category, isDeleted) VALUES (3, 'Test Thread', 1, 0)"))
+    discard executeQuery(ctx, parse("INSERT INTO category (id, name, description) VALUES (1, 'General', 'General discussion')"))
+
+    # This used to return 0 rows
+    let r = executeQuery(ctx, parse("SELECT thread.id, thread.name, category.id, category.name FROM thread, category WHERE thread.id = 3 AND thread.isDeleted = 0 AND thread.category = category.id"))
+    check r.success
+    check r.rows.len == 1
+
+  test "Multi-table join with aliases still works":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO thread (id, name, category, isDeleted) VALUES (3, 'Test Thread', 1, 0)"))
+    discard executeQuery(ctx, parse("INSERT INTO category (id, name, description) VALUES (1, 'General', 'General discussion')"))
+
+    let r = executeQuery(ctx, parse("SELECT t.id AS thread_id, t.name AS thread_name, c.id AS cat_id, c.name AS cat_name FROM thread t, category c WHERE t.id = 3 AND t.category = c.id"))
+    check r.success
+    check r.rows.len == 1
+    check r.columns == @["thread_id", "thread_name", "cat_id", "cat_name"]
+
+  test "Three-table join without aliases (Bug 4 - nkPath in column names)":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE post (id INTEGER PRIMARY KEY, author INTEGER, thread INTEGER, creation TEXT)"))
+    discard executeQuery(ctx, parse("INSERT INTO thread (id, name, category, isDeleted) VALUES (5, 'Thread5', 1, 0)"))
+    discard executeQuery(ctx, parse("INSERT INTO category (id, name, description) VALUES (1, 'Cat1', 'desc1')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (10, 'Alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO post (id, author, thread, creation) VALUES (100, 10, 5, '2024-06-01 12:00:00')"))
+
+    # Three-table join with nkPath references
+    let r = executeQuery(ctx, parse("SELECT post.id, post.creation, post.thread, users.id, users.name FROM post, users, thread WHERE post.thread = thread.id AND post.author = users.id AND post.id = 100"))
+    check r.success
+    check r.rows.len == 1
+    # Verify qualified column references resolve correctly
+    check valueToString(r.rows[0]["post.id"]) == "100"
+    check valueToString(r.rows[0]["users.name"]) == "Alice"
+    check valueToString(r.rows[0]["post.thread"]) == "5"
+    # Check column names don't contain "nkPath"
+    for col in r.columns:
+      check not col.contains("nkPath")
+
+  test "NOT IN (list) parses and executes":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (2, 'bob')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (3, 'charlie')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (4, 'dave')"))
+
+    let r = executeQuery(ctx, parse("SELECT id, name FROM users WHERE id NOT IN (1, 4)"))
+    check r.success
+    check r.rows.len == 2
+
+  test "NOT LIKE parses and executes":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (2, 'bob')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (3, 'charlie')"))
+
+    let r = executeQuery(ctx, parse("SELECT name FROM users WHERE name NOT LIKE 'a%'"))
+    check r.success
+    check r.rows.len == 2
+
+  test "NOT BETWEEN parses and executes":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (5, 'bob')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (10, 'charlie')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (15, 'dave')"))
+
+    let r = executeQuery(ctx, parse("SELECT id, name FROM users WHERE id NOT BETWEEN 3 AND 12"))
+    check r.success
+    check r.rows.len == 2
+
+  test "Multi-column ORDER BY sorts correctly":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (2, 'bob')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (3, 'alice')"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (4, 'charlie')"))
+
+    let r = executeQuery(ctx, parse("SELECT name, id FROM users ORDER BY name ASC, id DESC"))
+    check r.success
+    check r.rows.len == 4
+    # After sorting by name ASC, then id DESC within same name:
+    # alice(3), alice(1), bob(2), charlie(4)
+    check valueToString(r.rows[0]["id"]) == "3"
+    check valueToString(r.rows[1]["id"]) == "1"
+    check valueToString(r.rows[2]["id"]) == "2"
+    check valueToString(r.rows[3]["id"]) == "4"
+
+  test "Numeric != comparison is consistent with =":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    # 5.0 stored as string should equal integer 5 via numeric comparison
+    let r = executeQuery(ctx, parse("SELECT id, name FROM users WHERE id != 999"))
+    check r.success
+    # Should return all rows since none have id=999
+
+  test "Column alias consistency for table.column in getSelectColumns":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE posts (id INTEGER PRIMARY KEY, title TEXT)"))
+    discard executeQuery(ctx, parse("INSERT INTO posts (id, title) VALUES (1, 'Hello')"))
+
+    let r = executeQuery(ctx, parse("SELECT posts.id, posts.title FROM posts"))
+    check r.success
+    check r.rows.len == 1
+    # Column names should match the full path "posts.id", "posts.title"
+    check r.columns == @["posts.id", "posts.title"]
+    # Data should be accessible via both qualified and unqualified names
+    check valueToString(r.rows[0]["posts.id"]) == "1"
+
+  test "DELETE inside transaction actually removes row":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (10, 'temp')"))
+    # Verify row exists
+    let r1 = executeQuery(ctx, parse("SELECT * FROM users WHERE id = 10"))
+    check r1.success
+    check r1.rows.len == 1
+    # Delete within transaction
+    discard executeQuery(ctx, parse("BEGIN"))
+    let del = executeQuery(ctx, parse("DELETE FROM users WHERE id = 10"))
+    check del.success
+    discard executeQuery(ctx, parse("COMMIT"))
+    # Verify row is gone
+    let r2 = executeQuery(ctx, parse("SELECT * FROM users WHERE id = 10"))
+    check r2.success
+    check r2.rows.len == 0
+
+  test "PK-only row survives transaction commit":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE pksimple (id INTEGER PRIMARY KEY)"))
+    discard executeQuery(ctx, parse("BEGIN"))
+    discard executeQuery(ctx, parse("INSERT INTO pksimple (id) VALUES (1)"))
+    discard executeQuery(ctx, parse("COMMIT"))
+    let r = executeQuery(ctx, parse("SELECT * FROM pksimple WHERE id = 1"))
+    check r.success
+    check r.rows.len == 1
+
+  test "MIN and MAX skip NULL values":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE scores (id INTEGER PRIMARY KEY, val INTEGER)"))
+    discard executeQuery(ctx, parse("INSERT INTO scores (id, val) VALUES (1, 10)"))
+    discard executeQuery(ctx, parse("INSERT INTO scores (id, val) VALUES (2, NULL)"))
+    discard executeQuery(ctx, parse("INSERT INTO scores (id, val) VALUES (3, 30)"))
+    let rmin = executeQuery(ctx, parse("SELECT MIN(val) AS m FROM scores"))
+    check rmin.success
+    check rmin.rows.len == 1
+    check valueToString(rmin.rows[0]["m"]) == "10"
+    let rmax = executeQuery(ctx, parse("SELECT MAX(val) AS m FROM scores"))
+    check rmax.success
+    check rmax.rows.len == 1
+    check valueToString(rmax.rows[0]["m"]) == "30"

tests/join_tests.nim

@@ -3,6 +3,8 @@ import std/os
 import std/strutils
 import std/monotimes
 import std/tables
+import std/sequtils
+import barabadb/core/types
 import barabadb/query/executor as qexec
 import barabadb/query/parser
 import barabadb/storage/lsm
@@ -97,7 +99,7 @@ suite "JOIN execution":
     var foundBob = false
     for row in r.rows:
       if row["u.name"] == "Bob":
-        check row["x.total"] == "\\N"
+        check row["x.total"].kind == vkNull
         foundBob = true
     check foundBob
 

tests/test_all.nim

@@ -2831,7 +2831,7 @@ suite "Window Functions":
     # Sales: Diana(75000)=1, Charlie(70000)=2
     var found = initTable[string, string]()
     for row in r.rows:
-      found[row["name"]] = row["rn"]
+      found[$row["name"]] = $row["rn"]
     check found["Eve"] == "1"
     check found["Alice"] == "2"
     check found["Bob"] == "3"
@@ -3474,7 +3474,7 @@ suite "Auto-Increment & ID Generators":
     let r = qexec.executeQuery(ctx, parse("SELECT gen_random_uuid() AS uid"))
     check r.success
     check r.rows.len == 1
-    let uid = r.rows[0]["uid"]
+    let uid = $r.rows[0]["uid"]
     check uid.len == 36
     check uid[8] == '-'
     check uid[13] == '-'
@@ -3486,7 +3486,7 @@ suite "Auto-Increment & ID Generators":
     let r = qexec.executeQuery(ctx, parse("SELECT uuid() AS uid"))
     check r.success
     check r.rows.len == 1
-    check r.rows[0]["uid"].len == 36
+    check ($r.rows[0]["uid"]).len == 36
 
   test "Two UUIDs are different":
     let r = qexec.executeQuery(ctx, parse("SELECT uuid() AS a, uuid() AS b"))
@@ -3564,7 +3564,7 @@ suite "Auto-Increment & ID Generators":
     let r = qexec.executeQuery(ctx, parse("SELECT snowflake_id(1) AS sid"))
     check r.success
     check r.rows.len == 1
-    let sid = r.rows[0]["sid"]
+    let sid = $r.rows[0]["sid"]
     check sid.len > 0
     var num: int64 = 0
     try:
@@ -3720,17 +3720,17 @@ suite "Type Safety — evalExprValue":
     check r.success
     check r.rows[0]["r"] == "17.5"
 
-  test "evalExprValue returns correct Value kind for literals":
+  test "evalExpr returns correct Value kind for literals":
     let lit = IRExpr(kind: irekLiteral, valueKind: vkInt64)
     lit.literal = IRLiteral(kind: vkInt64, int64Val: 42)
-    let v = evalExprValue(lit, initTable[string, string](), nil)
+    let v = evalExpr(lit, initTable[string, Value](), nil)
     check v.kind == vkInt64
     check v.int64Val == 42
 
-  test "evalExprValue returns correct Value kind for float literal":
+  test "evalExpr returns correct Value kind for float literal":
     let lit = IRExpr(kind: irekLiteral, valueKind: vkFloat64)
     lit.literal = IRLiteral(kind: vkFloat64, float64Val: 3.14)
-    let v = evalExprValue(lit, initTable[string, string](), nil)
+    let v = evalExpr(lit, initTable[string, Value](), nil)
     check v.kind == vkFloat64
     check v.float64Val == 3.14
 
@@ -3998,7 +3998,7 @@ suite "Hybrid RAG Search":
     let r = qexec.executeQuery(ctx, parse("SELECT hybrid_search('docs', 'embedding', 'content', 'quick brown', '[1.0, 0.0, 0.0]', 10) AS res"))
     check r.success
     check r.rows.len == 1
-    let jsonStr = r.rows[0]["res"]
+    let jsonStr = $r.rows[0]["res"]
     check jsonStr.len > 2  # not "[]"
     let arr = parseJson(jsonStr)
     check arr.kind == JArray
@@ -4013,7 +4013,7 @@ suite "Hybrid RAG Search":
     let r = qexec.executeQuery(ctx, parse("SELECT hybrid_search_ids('docs2', 'embedding', 'content', 'machine learning', '[0.0, 1.0, 0.0]', 10) AS ids"))
     check r.success
     check r.rows.len == 1
-    let idsStr = r.rows[0]["ids"]
+    let idsStr = $r.rows[0]["ids"]
     check idsStr.len > 0
     check idsStr.contains("20")
 
@@ -4029,7 +4029,7 @@ suite "Hybrid RAG Search":
     discard qexec.executeQuery(ctx, parse("CREATE INDEX idx_fts3 ON docs3(content) USING FTS"))
     let r = qexec.executeQuery(ctx, parse("SELECT hybrid_search('docs3', 'embedding', 'content', 'quick brown fox', '[1.0, 0.0, 0.0]', 10) AS res"))
     check r.success
-    let arr = parseJson(r.rows[0]["res"])
+    let arr = parseJson($r.rows[0]["res"])
     check arr.len == 3
     # Doc 3 should be first (matches both vector and FTS), doc 1 second (vector only), doc 2 third (no match)
     check arr[0]["id"].getStr() == "3"
@@ -4038,7 +4038,7 @@ suite "Hybrid RAG Search":
     let r = qexec.executeQuery(ctx, parse("SELECT rerank('quick brown', '[{\"id\":\"1\",\"score\":\"0.5\"},{\"id\":\"2\",\"score\":\"0.5\"}]') AS res"))
     check r.success
     # Both have same score, rerank should preserve order (no content to boost)
-    let arr = parseJson(r.rows[0]["res"])
+    let arr = parseJson($r.rows[0]["res"])
     check arr.kind == JArray
     check arr.len == 2
 
@@ -4060,7 +4060,7 @@ suite "Hybrid RAG Search":
     discard qexec.executeQuery(ctx, parse("CREATE INDEX idx_fts5 ON docs5(content) USING FTS"))
     let r = qexec.executeQuery(ctx, parse("SELECT hybrid_search_filtered('docs5', 'embedding', 'content', 'quick brown fox', '[1.0, 0.0, 0.0]', 10, 'tenant_id', 'tenant-a') AS res"))
     check r.success
-    let arr = parseJson(r.rows[0]["res"])
+    let arr = parseJson($r.rows[0]["res"])
     # Doc 1 (tenant-a) should be first and highest scored; Doc 2 (tenant-b) must be excluded
     check arr[0]["id"].getStr() == "1"
     for elem in arr:
@@ -4074,6 +4074,6 @@ suite "Hybrid RAG Search":
     discard qexec.executeQuery(ctx, parse("CREATE INDEX idx_fts6 ON docs6(content) USING FTS"))
     let r = qexec.executeQuery(ctx, parse("SELECT hybrid_search_filtered('docs6', 'embedding', 'content', 'quick brown fox', '[1.0, 0.0, 0.0]', 10, '', '') AS res"))
     check r.success
-    let arr = parseJson(r.rows[0]["res"])
+    let arr = parseJson($r.rows[0]["res"])
     check arr.len == 2