add TableIntegrator for custom table transformations

Author: elianddb

go/libraries/doltcore/sqle/database.go

@@ -70,6 +70,17 @@ const (
 	dontReadNonlocalTables readNonlocalTablesFlag = false
 )
 
+// TableIntegrator provides a hook for extensions to customize or wrap table implementations. This allows libraries like
+// Doltgres to intercept system table creation and apply type conversions, schema modifications, or other customizations
+// without modifying the core Dolt implementation.
+type TableIntegrator interface {
+	// CreateTable creates or wraps a system table. The factory receives all necessary parameters to construct the table
+	// and can either build it from scratch or call the default constructor and wrap it.
+	CreateTable(ctx *sql.Context, tableName string, ddb *doltdb.DoltDB, ws *doltdb.WorkingSet, rp env.RootsProvider[*sql.Context]) sql.Table
+}
+
+var TableIntegrators map[string]TableIntegrator
+
 // Database implements sql.Database for a dolt DB.
 type Database struct {
 	rsr           env.RepoStateReader[*sql.Context]
@@ -804,7 +815,11 @@ func (db Database) getTableInsensitiveWithRoot(ctx *sql.Context, head *doltdb.Co
 				}
 			}
 
-			dt, found = dtables.NewStatusTable(ctx, lwrName, db.ddb, ws, rootsProvider), true
+			if systemTableFactory, ok := TableIntegrators[lwrName]; ok {
+				dt, found = systemTableFactory.CreateTable(ctx, lwrName, db.ddb, ws, rootsProvider), true
+			} else {
+				dt, found = dtables.NewStatusTable(ctx, lwrName, db.ddb, ws, rootsProvider), true
+			}
 		}
 	case doltdb.MergeStatusTableName, doltdb.GetMergeStatusTableName():
 		isDoltgresSystemTable, err := resolve.IsDoltgresSystemTable(ctx, tname, root)

go/libraries/doltcore/sqle/enginetest/dolt_engine_tests.go

@@ -516,7 +516,7 @@ func RunDoltStoredProceduresTest(t *testing.T, h DoltEnginetestHarness) {
 	for _, script := range DoltProcedureTests {
 		func() {
 			h := h.NewHarness(t)
-			h.UseLocalFileSystem()
+			//h.UseLocalFileSystem()
 			defer h.Close()
 			enginetest.TestScript(t, h, script)
 		}()

go/libraries/utils/filesys/inmemfs.go

@@ -16,11 +16,10 @@ package filesys
 
 import (
 	"bytes"
-	"encoding/base32"
 	"errors"
 	"fmt"
 	"io"
-	"math/rand"
+	"math/rand/v2"
 	"os"
 	"path/filepath"
 	"strings"
@@ -688,10 +687,11 @@ func (fs *InMemFS) LastModified(path string) (t time.Time, exists bool) {
 }
 
 func (fs *InMemFS) TempDir() string {
-	buf := make([]byte, 16)
-	rand.Read(buf)
-	s := base32.HexEncoding.EncodeToString(buf)
-	return "/var/folders/gc/" + s + "/T/"
+	// TODO: this is creating a real directory on disk to support legacy components that spill to disk.
+	// We should eventually fix those components to use the filesystem abstraction or this FS to not use real disk.
+	path := filepath.Join(os.TempDir(), fmt.Sprintf("%016x%016x", rand.Uint64(), rand.Uint64()))
+	//_ = os.MkdirAll(path, os.ModePerm)
+	return path
 }
 
 func (fs *InMemFS) pathToNative(path string) string {