[MEVD] Make PG schema nullable

Closes #11355

Author: roji

dotnet/src/VectorData/PgVector/PostgresCollection.cs

@@ -41,7 +41,7 @@ public class PostgresCollection<TKey, TRecord> : VectorStoreCollection<TKey, TRe
     private readonly string _databaseName;
 
     /// <summary>The database schema.</summary>
-    private readonly string _schema;
+    private readonly string? _schema;
 
     /// <summary>The model for this collection.</summary>
     private readonly CollectionModel _model;

dotnet/src/VectorData/PgVector/PostgresCollectionOptions.cs

@@ -20,11 +20,11 @@ public PostgresCollectionOptions()
 
     internal PostgresCollectionOptions(PostgresCollectionOptions? source) : base(source)
     {
-        this.Schema = source?.Schema ?? PostgresVectorStoreOptions.Default.Schema;
+        this.Schema = source?.Schema;
     }
 
     /// <summary>
     /// Gets or sets the database schema.
     /// </summary>
-    public string Schema { get; set; } = PostgresVectorStoreOptions.Default.Schema;
+    public string? Schema { get; set; }
 }

dotnet/src/VectorData/PgVector/PostgresSqlBuilder.cs

@@ -20,33 +20,36 @@ namespace Microsoft.SemanticKernel.Connectors.PgVector;
 [System.Diagnostics.CodeAnalysis.SuppressMessage("Security", "CA2100:Review SQL queries for security vulnerabilities", Justification = "We need to build the full table name using schema and collection, it does not support parameterized passing.")]
 internal static class PostgresSqlBuilder
 {
-    internal static void BuildDoesTableExistCommand(NpgsqlCommand command, string schema, string tableName)
+    internal static void BuildDoesTableExistCommand(NpgsqlCommand command, string? schema, string tableName)
     {
-        command.CommandText = """
-SELECT table_name
-FROM information_schema.tables
-WHERE table_schema = $1
-    AND table_type = 'BASE TABLE'
-    AND table_name = $2
-""";
-
         Debug.Assert(command.Parameters.Count == 0);
-        command.Parameters.Add(new() { Value = schema });
+
+        command.CommandText = """
+            SELECT table_name
+            FROM information_schema.tables
+            WHERE table_schema = $1
+                AND table_type = 'BASE TABLE'
+                AND table_name = $2
+            """;
+
+        command.Parameters.Add(new() { Value = schema ?? "public" });
         command.Parameters.Add(new() { Value = tableName });
     }
 
-    internal static void BuildGetTablesCommand(NpgsqlCommand command, string schema)
+    internal static void BuildGetTablesCommand(NpgsqlCommand command, string? schema)
     {
-        command.CommandText = """
-SELECT table_name
-FROM information_schema.tables
-WHERE table_schema = $1 AND table_type = 'BASE TABLE'
-""";
         Debug.Assert(command.Parameters.Count == 0);
-        command.Parameters.Add(new() { Value = schema });
+
+        command.CommandText = """
+            SELECT table_name
+            FROM information_schema.tables
+            WHERE table_schema = $1 AND table_type = 'BASE TABLE'
+            """;
+
+        command.Parameters.Add(new() { Value = schema ?? "public" });
     }
 
-    internal static string BuildCreateTableSql(string schema, string tableName, CollectionModel model, Version pgVersion, bool ifNotExists = true)
+    internal static string BuildCreateTableSql(string? schema, string tableName, CollectionModel model, Version pgVersion, bool ifNotExists = true)
     {
         if (string.IsNullOrWhiteSpace(tableName))
         {
@@ -61,7 +64,7 @@ internal static string BuildCreateTableSql(string schema, string tableName, Coll
         {
             createTableCommand.Append("IF NOT EXISTS ");
         }
-        createTableCommand.AppendIdentifier(schema).Append('.').AppendIdentifier(tableName).AppendLine(" (");
+        createTableCommand.AppendTableName(schema, tableName).AppendLine(" (");
 
         // Add the key column
         var keyStoreType = PostgresPropertyMapping.GetPostgresTypeName(model.KeyProperty).PgType;
@@ -119,7 +122,7 @@ internal static string BuildCreateTableSql(string schema, string tableName, Coll
     }
 
     /// <inheritdoc />
-    internal static string BuildCreateIndexSql(string schema, string tableName, string columnName, string indexKind, string distanceFunction, bool isVector, bool isFullText, string? fullTextLanguage, bool ifNotExists)
+    internal static string BuildCreateIndexSql(string? schema, string tableName, string columnName, string indexKind, string distanceFunction, bool isVector, bool isFullText, string? fullTextLanguage, bool ifNotExists)
     {
         var indexName = $"{tableName}_{columnName}_index";
 
@@ -134,14 +137,14 @@ internal static string BuildCreateIndexSql(string schema, string tableName, stri
         {
             // Create a GIN index for full-text search
             var language = fullTextLanguage ?? PostgresConstants.DefaultFullTextSearchLanguage;
-            sql.AppendIdentifier(indexName).Append(" ON ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName)
+            sql.AppendIdentifier(indexName).Append(" ON ").AppendTableName(schema, tableName)
                 .Append(" USING GIN (to_tsvector(").AppendLiteral(language).Append(", ").AppendIdentifier(columnName).Append("))");
             return sql.ToString();
         }
 
         if (!isVector)
         {
-            sql.AppendIdentifier(indexName).Append(" ON ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName)
+            sql.AppendIdentifier(indexName).Append(" ON ").AppendTableName(schema, tableName)
                 .Append(" (").AppendIdentifier(columnName).Append(')');
             return sql.ToString();
         }
@@ -167,23 +170,23 @@ internal static string BuildCreateIndexSql(string schema, string tableName, stri
             _ => throw new NotSupportedException($"Distance function {distanceFunction} is not supported.")
         };
 
-        sql.AppendIdentifier(indexName).Append(" ON ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName)
+        sql.AppendIdentifier(indexName).Append(" ON ").AppendTableName(schema, tableName)
             .Append(" USING ").Append(indexTypeName).Append(" (").AppendIdentifier(columnName).Append(' ').Append(indexOps).Append(')');
         return sql.ToString();
     }
 
     /// <inheritdoc />
-    internal static void BuildDropTableCommand(NpgsqlCommand command, string schema, string tableName)
+    internal static void BuildDropTableCommand(NpgsqlCommand command, string? schema, string tableName)
     {
         StringBuilder sql = new();
-        sql.Append("DROP TABLE IF EXISTS ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName);
+        sql.Append("DROP TABLE IF EXISTS ").AppendTableName(schema, tableName);
         command.CommandText = sql.ToString();
     }
 
     /// <inheritdoc />
     internal static bool BuildUpsertCommand<TKey>(
         NpgsqlBatch batch,
-        string schema,
+        string? schema,
         string tableName,
         CollectionModel model,
         IEnumerable<object> records,
@@ -260,9 +263,7 @@ string GenerateSingleUpsertSql(bool autoGeneratedKey)
 
             sqlBuilder
                 .Append("INSERT INTO ")
-                .AppendIdentifier(schema)
-                .Append('.')
-                .AppendIdentifier(tableName)
+                .AppendTableName(schema, tableName)
                 .Append(" (");
 
             var i = 0;
@@ -345,7 +346,7 @@ string GenerateSingleUpsertSql(bool autoGeneratedKey)
     }
 
     /// <inheritdoc />
-    internal static void BuildGetCommand<TKey>(NpgsqlCommand command, string schema, string tableName, CollectionModel model, TKey key, bool includeVectors = false)
+    internal static void BuildGetCommand<TKey>(NpgsqlCommand command, string? schema, string tableName, CollectionModel model, TKey key, bool includeVectors = false)
         where TKey : notnull
     {
         StringBuilder sql = new();
@@ -360,7 +361,7 @@ internal static void BuildGetCommand<TKey>(NpgsqlCommand command, string schema,
             sql.AppendIdentifier(model.Properties[i].StorageName);
         }
 
-        sql.AppendLine().Append("FROM ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName).AppendLine()
+        sql.AppendLine().Append("FROM ").AppendTableName(schema, tableName).AppendLine()
             .Append("WHERE ").AppendIdentifier(model.KeyProperty.StorageName).Append(" = $1;");
 
         command.CommandText = sql.ToString();
@@ -369,7 +370,7 @@ internal static void BuildGetCommand<TKey>(NpgsqlCommand command, string schema,
     }
 
     /// <inheritdoc />
-    internal static void BuildGetBatchCommand<TKey>(NpgsqlCommand command, string schema, string tableName, CollectionModel model, List<TKey> keys, bool includeVectors = false)
+    internal static void BuildGetBatchCommand<TKey>(NpgsqlCommand command, string? schema, string tableName, CollectionModel model, List<TKey> keys, bool includeVectors = false)
         where TKey : notnull
     {
         NpgsqlDbType? keyType = PostgresPropertyMapping.GetNpgsqlDbType(model.KeyProperty) ?? throw new UnreachableException($"Unsupported key type {model.KeyProperty.Type.Name}");
@@ -393,7 +394,7 @@ internal static void BuildGetBatchCommand<TKey>(NpgsqlCommand command, string sc
             sql.AppendIdentifier(property.StorageName);
         }
 
-        sql.AppendLine().Append("FROM ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName).AppendLine()
+        sql.AppendLine().Append("FROM ").AppendTableName(schema, tableName).AppendLine()
             .Append("WHERE ").AppendIdentifier(model.KeyProperty.StorageName).Append(" = ANY($1);");
 
         command.CommandText = sql.ToString();
@@ -406,10 +407,10 @@ internal static void BuildGetBatchCommand<TKey>(NpgsqlCommand command, string sc
     }
 
     /// <inheritdoc />
-    internal static void BuildDeleteCommand<TKey>(NpgsqlCommand command, string schema, string tableName, string keyColumn, TKey key)
+    internal static void BuildDeleteCommand<TKey>(NpgsqlCommand command, string? schema, string tableName, string keyColumn, TKey key)
     {
         StringBuilder sql = new();
-        sql.Append("DELETE FROM ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName).AppendLine()
+        sql.Append("DELETE FROM ").AppendTableName(schema, tableName).AppendLine()
             .Append("WHERE ").AppendIdentifier(keyColumn).Append(" = $1;");
 
         command.CommandText = sql.ToString();
@@ -418,7 +419,7 @@ internal static void BuildDeleteCommand<TKey>(NpgsqlCommand command, string sche
     }
 
     /// <inheritdoc />
-    internal static void BuildDeleteBatchCommand<TKey>(NpgsqlCommand command, string schema, string tableName, KeyPropertyModel keyProperty, List<TKey> keys)
+    internal static void BuildDeleteBatchCommand<TKey>(NpgsqlCommand command, string? schema, string tableName, KeyPropertyModel keyProperty, List<TKey> keys)
     {
         NpgsqlDbType? keyType = PostgresPropertyMapping.GetNpgsqlDbType(keyProperty) ?? throw new ArgumentException($"Unsupported key type {typeof(TKey).Name}");
 
@@ -431,7 +432,7 @@ internal static void BuildDeleteBatchCommand<TKey>(NpgsqlCommand command, string
         }
 
         StringBuilder sql = new();
-        sql.Append("DELETE FROM ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName).AppendLine()
+        sql.Append("DELETE FROM ").AppendTableName(schema, tableName).AppendLine()
             .Append("WHERE ").AppendIdentifier(keyProperty.StorageName).Append(" = ANY($1);");
 
         command.CommandText = sql.ToString();
@@ -504,7 +505,7 @@ private static (string Condition, List<object> Parameters) GenerateFilterConditi
 #pragma warning disable CS0618 // VectorSearchFilter is obsolete
     /// <inheritdoc />
     internal static void BuildGetNearestMatchCommand<TRecord>(
-        NpgsqlCommand command, string schema, string tableName, CollectionModel model, VectorPropertyModel vectorProperty, object vectorValue,
+        NpgsqlCommand command, string? schema, string tableName, CollectionModel model, VectorPropertyModel vectorProperty, object vectorValue,
         VectorSearchFilter? legacyFilter, Expression<Func<TRecord, bool>>? newFilter, int? skip, bool includeVectors, int limit,
         double? scoreThreshold = null)
     {
@@ -528,7 +529,7 @@ internal static void BuildGetNearestMatchCommand<TRecord>(
         StringBuilder sql = new();
         sql.Append("SELECT ").Append(columns).Append(", ").AppendIdentifier(vectorProperty.StorageName)
             .Append(' ').Append(distanceOp).Append(" $1 AS ").AppendIdentifier(PostgresConstants.DistanceColumnName).AppendLine()
-            .Append("FROM ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName)
+            .Append("FROM ").AppendTableName(schema, tableName)
             .Append(' ').AppendLine(where)
             .Append("ORDER BY ").AppendLine(PostgresConstants.DistanceColumnName)
             .Append("LIMIT ").Append(limit);
@@ -608,7 +609,7 @@ or DistanceFunction.HammingDistance
     }
 
     internal static void BuildSelectWhereCommand<TRecord>(
-        NpgsqlCommand command, string schema, string tableName, CollectionModel model,
+        NpgsqlCommand command, string? schema, string tableName, CollectionModel model,
         Expression<Func<TRecord, bool>> filter, int top, FilteredRecordRetrievalOptions<TRecord> options)
     {
         StringBuilder query = new(200);
@@ -627,7 +628,7 @@ internal static void BuildSelectWhereCommand<TRecord>(
             }
         }
         query.AppendLine();
-        query.Append("FROM ").AppendIdentifier(schema).Append('.').AppendIdentifier(tableName).AppendLine();
+        query.Append("FROM ").AppendTableName(schema, tableName).AppendLine();
 
         PostgresFilterTranslator translator = new(model, filter, startParamIndex: 1, query);
         translator.Translate(appendWhere: true);
@@ -678,6 +679,19 @@ internal static (string Condition, List<object> Parameters) GenerateNewFilterCon
         return (translator.Clause.ToString(), translator.ParameterValues);
     }
 
+    /// <summary>
+    /// Appends a schema-qualified table name. If schema is null or empty, omits the schema prefix.
+    /// </summary>
+    private static StringBuilder AppendTableName(this StringBuilder sb, string? schema, string tableName)
+    {
+        if (!string.IsNullOrEmpty(schema))
+        {
+            sb.AppendIdentifier(schema!).Append('.');
+        }
+
+        return sb.AppendIdentifier(tableName);
+    }
+
 #pragma warning disable CS0618 // VectorSearchFilter is obsolete
     internal static (string Clause, List<object> Parameters) GenerateLegacyFilterWhereClause(CollectionModel model, VectorSearchFilter legacyFilter, int startParamIndex)
     {
@@ -739,7 +753,7 @@ internal static (string Condition, List<object> Parameters) GenerateLegacyFilter
     /// Builds a hybrid search command that combines vector similarity search with full-text keyword search using RRF (Reciprocal Rank Fusion).
     /// </summary>
     internal static void BuildHybridSearchCommand<TRecord>(
-        NpgsqlCommand command, string schema, string tableName, CollectionModel model,
+        NpgsqlCommand command, string? schema, string tableName, CollectionModel model,
         VectorPropertyModel vectorProperty, DataPropertyModel textProperty,
         object vectorValue, ICollection<string> keywords,
         VectorSearchFilter? legacyFilter, Expression<Func<TRecord, bool>>? newFilter,
@@ -773,7 +787,7 @@ internal static void BuildHybridSearchCommand<TRecord>(
 
         // Build the full table name
         var fullTableName = new StringBuilder()
-            .AppendIdentifier(schema).Append('.').AppendIdentifier(tableName)
+            .AppendTableName(schema, tableName)
             .ToString();
 
         // Use a larger internal limit for the CTEs to get better ranking, then limit final results

dotnet/src/VectorData/PgVector/PostgresVectorStore.cs

@@ -30,7 +30,7 @@ public sealed class PostgresVectorStore : VectorStore
     private readonly string _databaseName;
 
     /// <summary>The database schema.</summary>
-    private readonly string _schema;
+    private readonly string? _schema;
 
     private readonly IEmbeddingGenerator? _embeddingGenerator;
 
@@ -44,7 +44,7 @@ public PostgresVectorStore(NpgsqlDataSource dataSource, bool ownsDataSource, Pos
     {
         Verify.NotNull(dataSource);
 
-        this._schema = options?.Schema ?? PostgresVectorStoreOptions.Default.Schema;
+        this._schema = options?.Schema;
         this._embeddingGenerator = options?.EmbeddingGenerator;
         this._dataSource = dataSource;
         this._dataSourceArc = ownsDataSource ? new NpgsqlDataSourceArc(dataSource) : null;

dotnet/src/VectorData/PgVector/PostgresVectorStoreOptions.cs

@@ -20,14 +20,14 @@ public PostgresVectorStoreOptions()
 
     internal PostgresVectorStoreOptions(PostgresVectorStoreOptions? source)
     {
-        this.Schema = source?.Schema ?? Default.Schema;
+        this.Schema = source?.Schema;
         this.EmbeddingGenerator = source?.EmbeddingGenerator;
     }
 
     /// <summary>
     /// Gets or sets the database schema.
     /// </summary>
-    public string Schema { get; set; } = "public";
+    public string? Schema { get; set; }
 
     /// <summary>
     /// Gets or sets the default embedding generator to use when generating vectors embeddings with this vector store.