sql: support hash sharded index default bucket count

Fixes #74739

Release not (sql change): We used to always create hash sharded
index by specifying a bucket count. With this change, user does
not need to do that anymore. Hash index can be created with just
`USING HASH` instead of `USING HASH WITH BUCKET_COUNT = xxx`. A
default bucket count 8 will be used.

docs/generated/settings/settings-for-tenants.txt

@@ -87,6 +87,7 @@ sql.cross_db_sequence_references.enabled	boolean	false	if true, sequences refere
 sql.cross_db_views.enabled	boolean	false	if true, creating views that refer to other databases is allowed
 sql.defaults.datestyle	enumeration	iso, mdy	default value for DateStyle session setting [iso, mdy = 0, iso, dmy = 1, iso, ymd = 2]
 sql.defaults.datestyle.enabled	boolean	false	default value for datestyle_enabled session setting
+sql.defaults.default_hash_sharded_index_bucket_count	integer	8	used as bucket count if bucket count is not specified in hash sharded index definition
 sql.defaults.default_int_size	integer	8	the size, in bytes, of an INT type
 sql.defaults.disallow_full_table_scans.enabled	boolean	false	setting to true rejects queries that have planned a full table scan
 sql.defaults.distsql	enumeration	auto	default distributed SQL execution mode [off = 0, auto = 1, on = 2, always = 3]

docs/generated/settings/settings.html

@@ -94,6 +94,7 @@
 <tr><td><code>sql.cross_db_views.enabled</code></td><td>boolean</td><td><code>false</code></td><td>if true, creating views that refer to other databases is allowed</td></tr>
 <tr><td><code>sql.defaults.datestyle</code></td><td>enumeration</td><td><code>iso, mdy</code></td><td>default value for DateStyle session setting [iso, mdy = 0, iso, dmy = 1, iso, ymd = 2]</td></tr>
 <tr><td><code>sql.defaults.datestyle.enabled</code></td><td>boolean</td><td><code>false</code></td><td>default value for datestyle_enabled session setting</td></tr>
+<tr><td><code>sql.defaults.default_hash_sharded_index_bucket_count</code></td><td>integer</td><td><code>8</code></td><td>used as bucket count if bucket count is not specified in hash sharded index definition</td></tr>
 <tr><td><code>sql.defaults.default_int_size</code></td><td>integer</td><td><code>8</code></td><td>the size, in bytes, of an INT type</td></tr>
 <tr><td><code>sql.defaults.disallow_full_table_scans.enabled</code></td><td>boolean</td><td><code>false</code></td><td>setting to true rejects queries that have planned a full table scan</td></tr>
 <tr><td><code>sql.defaults.distsql</code></td><td>enumeration</td><td><code>auto</code></td><td>default distributed SQL execution mode [off = 0, auto = 1, on = 2, always = 3]</td></tr>

docs/generated/sql/bnf/alter_primary_key.bnf

@@ -1,5 +1,7 @@
 alter_onetable_stmt ::=
 	'ALTER' 'TABLE' table_name 'ALTER' 'PRIMARY' 'KEY' 'USING' 'COLUMNS' '(' index_params ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets
+	| 'ALTER' 'TABLE' table_name 'ALTER' 'PRIMARY' 'KEY' 'USING' 'COLUMNS' '(' index_params ')' 'USING' 'HASH'
 	| 'ALTER' 'TABLE' table_name 'ALTER' 'PRIMARY' 'KEY' 'USING' 'COLUMNS' '(' index_params ')' 
 	| 'ALTER' 'TABLE' 'IF' 'EXISTS' table_name 'ALTER' 'PRIMARY' 'KEY' 'USING' 'COLUMNS' '(' index_params ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets
+	| 'ALTER' 'TABLE' 'IF' 'EXISTS' table_name 'ALTER' 'PRIMARY' 'KEY' 'USING' 'COLUMNS' '(' index_params ')' 'USING' 'HASH'
 	| 'ALTER' 'TABLE' 'IF' 'EXISTS' table_name 'ALTER' 'PRIMARY' 'KEY' 'USING' 'COLUMNS' '(' index_params ')' 

docs/generated/sql/bnf/col_qualification.bnf

@@ -4,6 +4,7 @@ col_qualification ::=
 	| 'CONSTRAINT' constraint_name 'NOT' 'VISIBLE'
 	| 'CONSTRAINT' constraint_name 'UNIQUE'
 	| 'CONSTRAINT' constraint_name 'PRIMARY' 'KEY'
+	| 'CONSTRAINT' constraint_name 'PRIMARY' 'KEY' 'USING' 'HASH'
 	| 'CONSTRAINT' constraint_name 'PRIMARY' 'KEY' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets
 	| 'CONSTRAINT' constraint_name 'CHECK' '(' a_expr ')'
 	| 'CONSTRAINT' constraint_name 'DEFAULT' b_expr
@@ -20,6 +21,7 @@ col_qualification ::=
 	| 'NOT' 'VISIBLE'
 	| 'UNIQUE'
 	| 'PRIMARY' 'KEY'
+	| 'PRIMARY' 'KEY' 'USING' 'HASH'
 	| 'PRIMARY' 'KEY' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets
 	| 'CHECK' '(' a_expr ')'
 	| 'DEFAULT' b_expr

docs/generated/sql/bnf/create_index_stmt.bnf

@@ -1,5 +1,5 @@
 create_index_stmt ::=
-	'CREATE' ( 'UNIQUE' |  ) 'INDEX' ( 'CONCURRENTLY' |  ) opt_index_name 'ON' table_name ( 'USING' name |  ) '(' ( ( ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) ( ( ',' ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) )* ) ')' ( 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets |  ) ( ( 'COVERING' | 'STORING' | 'INCLUDE' ) '(' name_list ')' |  ) opt_partition_by_index ( 'WITH' '(' ( ( storage_parameter ) ( ( ',' storage_parameter ) )* ) ')' ) opt_where_clause
-	| 'CREATE' ( 'UNIQUE' |  ) 'INDEX' ( 'CONCURRENTLY' |  ) 'IF' 'NOT' 'EXISTS' index_name 'ON' table_name ( 'USING' name |  ) '(' ( ( ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) ( ( ',' ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) )* ) ')' ( 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets |  ) ( ( 'COVERING' | 'STORING' | 'INCLUDE' ) '(' name_list ')' |  ) opt_partition_by_index ( 'WITH' '(' ( ( storage_parameter ) ( ( ',' storage_parameter ) )* ) ')' ) opt_where_clause
+	'CREATE' ( 'UNIQUE' |  ) 'INDEX' ( 'CONCURRENTLY' |  ) opt_index_name 'ON' table_name ( 'USING' name |  ) '(' ( ( ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) ( ( ',' ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) )* ) ')' ( 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets | 'USING' 'HASH' |  ) ( ( 'COVERING' | 'STORING' | 'INCLUDE' ) '(' name_list ')' |  ) opt_partition_by_index ( 'WITH' '(' ( ( storage_parameter ) ( ( ',' storage_parameter ) )* ) ')' ) opt_where_clause
+	| 'CREATE' ( 'UNIQUE' |  ) 'INDEX' ( 'CONCURRENTLY' |  ) 'IF' 'NOT' 'EXISTS' index_name 'ON' table_name ( 'USING' name |  ) '(' ( ( ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) ( ( ',' ( func_expr_windowless index_elem_options | '(' a_expr ')' index_elem_options | name index_elem_options ) ) )* ) ')' ( 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets | 'USING' 'HASH' |  ) ( ( 'COVERING' | 'STORING' | 'INCLUDE' ) '(' name_list ')' |  ) opt_partition_by_index ( 'WITH' '(' ( ( storage_parameter ) ( ( ',' storage_parameter ) )* ) ')' ) opt_where_clause
 
 

docs/generated/sql/bnf/index_def.bnf

@@ -3,6 +3,10 @@ index_def ::=
 	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets 'STORING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets 'INCLUDE' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets  opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'COVERING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'STORING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'INCLUDE' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH'  opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')'  'COVERING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')'  'STORING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')'  'INCLUDE' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
@@ -11,6 +15,10 @@ index_def ::=
 	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets 'STORING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets 'INCLUDE' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets  opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'COVERING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'STORING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH' 'INCLUDE' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
+	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')' 'USING' 'HASH'  opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')'  'COVERING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')'  'STORING' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause
 	| 'UNIQUE' 'INDEX' opt_index_name '(' index_elem ( ( ',' index_elem ) )* ')'  'INCLUDE' '(' name_list ')' opt_partition_by_index opt_with_storage_parameter_list opt_where_clause

docs/generated/sql/bnf/stmt_block.bnf

@@ -1979,6 +1979,7 @@ index_params ::=
 
 opt_hash_sharded ::=
 	'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' a_expr
+	| 'USING' 'HASH'
 	| 
 
 opt_storing ::=
@@ -3307,6 +3308,7 @@ col_qualification_elem ::=
 	| 'NOT' 'VISIBLE'
 	| 'UNIQUE'
 	| 'PRIMARY' 'KEY'
+	| 'PRIMARY' 'KEY' 'USING' 'HASH'
 	| 'PRIMARY' 'KEY' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' a_expr
 	| 'CHECK' '(' a_expr ')'
 	| 'DEFAULT' b_expr

docs/generated/sql/bnf/table_constraint.bnf

@@ -5,6 +5,7 @@ table_constraint ::=
 	| 'CONSTRAINT' constraint_name 'UNIQUE' '(' index_params ')' 'INCLUDE' '(' name_list ')' opt_partition_by_index opt_where_clause
 	| 'CONSTRAINT' constraint_name 'UNIQUE' '(' index_params ')'  opt_partition_by_index opt_where_clause
 	| 'CONSTRAINT' constraint_name 'PRIMARY' 'KEY' '(' index_params ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets
+	| 'CONSTRAINT' constraint_name 'PRIMARY' 'KEY' '(' index_params ')' 'USING' 'HASH'
 	| 'CONSTRAINT' constraint_name 'PRIMARY' 'KEY' '(' index_params ')' 
 	| 'CONSTRAINT' constraint_name 'FOREIGN' 'KEY' '(' name_list ')' 'REFERENCES' table_name opt_column_list key_match reference_actions
 	| 'CHECK' '(' a_expr ')'
@@ -13,5 +14,6 @@ table_constraint ::=
 	| 'UNIQUE' '(' index_params ')' 'INCLUDE' '(' name_list ')' opt_partition_by_index opt_where_clause
 	| 'UNIQUE' '(' index_params ')'  opt_partition_by_index opt_where_clause
 	| 'PRIMARY' 'KEY' '(' index_params ')' 'USING' 'HASH' 'WITH' 'BUCKET_COUNT' '=' n_buckets
+	| 'PRIMARY' 'KEY' '(' index_params ')' 'USING' 'HASH'
 	| 'PRIMARY' 'KEY' '(' index_params ')' 
 	| 'FOREIGN' 'KEY' '(' name_list ')' 'REFERENCES' table_name opt_column_list key_match reference_actions

pkg/sql/catalog/catconstants/BUILD.bazel

@@ -12,5 +12,6 @@ go_library(
     deps = [
         "//pkg/clusterversion",
         "//pkg/keys",
+        "//pkg/settings",
     ],
 )

pkg/sql/catalog/catconstants/constants.go

@@ -10,7 +10,11 @@
 
 package catconstants
 
-import "math"
+import (
+	"math"
+
+	"github.com/cockroachdb/cockroach/pkg/settings"
+)
 
 // ReportableAppNamePrefix indicates that the application name can be
 // reported in telemetry without scrubbing. (Note this only applies to
@@ -370,3 +374,14 @@ const (
 	PgExtensionSpatialRefSysTableID
 	MinVirtualID = PgExtensionSpatialRefSysTableID
 )
+
+// DefaultHashShardedIndexBucketCount is the cluster setting of default bucket
+// count for hash sharded index when bucket count is not specified in index
+// definition.
+var DefaultHashShardedIndexBucketCount = settings.RegisterIntSetting(
+	settings.TenantWritable,
+	"sql.defaults.default_hash_sharded_index_bucket_count",
+	"used as bucket count if bucket count is not specified in hash sharded index definition",
+	8,
+	settings.NonNegativeInt,
+).WithPublic()

pkg/sql/catalog/tabledesc/table.go

@@ -18,6 +18,7 @@ import (
 	"strings"
 
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog"
+	"github.com/cockroachdb/cockroach/pkg/sql/catalog/catconstants"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/catpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
@@ -221,18 +222,24 @@ func MakeColumnDefDescs(
 func EvalShardBucketCount(
 	ctx context.Context, semaCtx *tree.SemaContext, evalCtx *tree.EvalContext, shardBuckets tree.Expr,
 ) (int32, error) {
+	var buckets int64
 	const invalidBucketCountMsg = `BUCKET_COUNT must be a 32-bit integer greater than 1, got %v`
-	typedExpr, err := schemaexpr.SanitizeVarFreeExpr(
-		ctx, shardBuckets, types.Int, "BUCKET_COUNT", semaCtx, tree.VolatilityVolatile,
-	)
-	if err != nil {
-		return 0, err
-	}
-	d, err := typedExpr.Eval(evalCtx)
-	if err != nil {
-		return 0, pgerror.Wrapf(err, pgcode.InvalidParameterValue, invalidBucketCountMsg, typedExpr)
+	// If shardBuckets is not specified, use default bucket count from cluster setting.
+	if _, ok := shardBuckets.(tree.DefaultVal); ok {
+		buckets = catconstants.DefaultHashShardedIndexBucketCount.Get(&evalCtx.Settings.SV)
+	} else {
+		typedExpr, err := schemaexpr.SanitizeVarFreeExpr(
+			ctx, shardBuckets, types.Int, "BUCKET_COUNT", semaCtx, tree.VolatilityVolatile,
+		)
+		if err != nil {
+			return 0, err
+		}
+		d, err := typedExpr.Eval(evalCtx)
+		if err != nil {
+			return 0, pgerror.Wrapf(err, pgcode.InvalidParameterValue, invalidBucketCountMsg, typedExpr)
+		}
+		buckets = int64(tree.MustBeDInt(d))
 	}
-	buckets := tree.MustBeDInt(d)
 	if buckets < 2 {
 		return 0, pgerror.Newf(pgcode.InvalidParameterValue, invalidBucketCountMsg, buckets)
 	}

pkg/sql/logictest/testdata/logic_test/hash_sharded_index

@@ -939,3 +939,49 @@ t_hash_pre_split  92        t_hash_pre_split_idx_b  /Table/92/2/4  /Table/92/2/5
 t_hash_pre_split  92        t_hash_pre_split_idx_b  /Table/92/2/5  /Table/92/2/6
 t_hash_pre_split  92        t_hash_pre_split_idx_b  /Table/92/2/6  /Table/92/2/7
 t_hash_pre_split  92        t_hash_pre_split_idx_b  /Table/92/2/7  /Max
+
+subtest test_default_bucket_count
+
+statement ok
+CREATE TABLE t_default_bucket_8 (
+  a INT PRIMARY KEY USING HASH,
+  b INT,
+  c INT,
+  INDEX idx_t_default_bucket_8_b (b) USING HASH,
+  INDEX idx_t_default_bucket_8_c (c) USING HASH WITH BUCKET_COUNT = 4,
+  FAMILY fam_0_a (a),
+  FAMILY fam_1_c_b (c, b)
+);
+
+query T
+SELECT @2 FROM [SHOW CREATE TABLE t_default_bucket_8]
+----
+CREATE TABLE public.t_default_bucket_8 (
+   crdb_internal_a_shard_8 INT4 NOT VISIBLE NOT NULL AS (mod(fnv32(crdb_internal.datums_to_bytes(a)), 8:::INT8)) VIRTUAL,
+   a INT8 NOT NULL,
+   b INT8 NULL,
+   c INT8 NULL,
+   crdb_internal_b_shard_8 INT4 NOT VISIBLE NOT NULL AS (mod(fnv32(crdb_internal.datums_to_bytes(b)), 8:::INT8)) VIRTUAL,
+   crdb_internal_c_shard_4 INT4 NOT VISIBLE NOT NULL AS (mod(fnv32(crdb_internal.datums_to_bytes(c)), 4:::INT8)) VIRTUAL,
+   CONSTRAINT t_default_bucket_8_pkey PRIMARY KEY (a ASC) USING HASH WITH BUCKET_COUNT = 8,
+   INDEX idx_t_default_bucket_8_b (b ASC) USING HASH WITH BUCKET_COUNT = 8,
+   INDEX idx_t_default_bucket_8_c (c ASC) USING HASH WITH BUCKET_COUNT = 4,
+   FAMILY fam_0_a (a),
+   FAMILY fam_1_c_b (c, b)
+)
+
+statement ok
+SET CLUSTER SETTING sql.defaults.default_hash_sharded_index_bucket_count = 16
+
+statement ok
+CREATE TABLE t_default_bucket_16 (a INT PRIMARY KEY USING HASH);
+
+query T
+SELECT @2 FROM [SHOW CREATE TABLE t_default_bucket_16]
+----
+CREATE TABLE public.t_default_bucket_16 (
+   crdb_internal_a_shard_16 INT4 NOT VISIBLE NOT NULL AS (mod(fnv32(crdb_internal.datums_to_bytes(a)), 16:::INT8)) VIRTUAL,
+   a INT8 NOT NULL,
+   CONSTRAINT t_default_bucket_16_pkey PRIMARY KEY (a ASC) USING HASH WITH BUCKET_COUNT = 16,
+   FAMILY "primary" (a)
+)

pkg/sql/parser/lexer.go

@@ -112,7 +112,7 @@ func (l *lexer) Lex(lval *sqlSymType) int {
 
 		case WITH:
 			switch nextID {
-			case TIME, ORDINALITY:
+			case TIME, ORDINALITY, BUCKET_COUNT:
 				lval.id = WITH_LA
 			}
 		case NULLS:

pkg/sql/parser/sql.y

@@ -6957,7 +6957,14 @@ col_qualification_elem:
   {
     $$.val = tree.PrimaryKeyConstraint{}
   }
-| PRIMARY KEY USING HASH WITH BUCKET_COUNT '=' a_expr
+| PRIMARY KEY USING HASH
+{
+  $$.val = tree.ShardedPrimaryKeyConstraint{
+    Sharded: true,
+    ShardBuckets: tree.DefaultVal{},
+  }
+}
+| PRIMARY KEY USING HASH WITH_LA BUCKET_COUNT '=' a_expr
 {
   $$.val = tree.ShardedPrimaryKeyConstraint{
     Sharded: true,
@@ -7285,12 +7292,19 @@ opt_storing:
   }
 
 opt_hash_sharded:
-  USING HASH WITH BUCKET_COUNT '=' a_expr
+  USING HASH WITH_LA BUCKET_COUNT '=' a_expr
   {
     $$.val = &tree.ShardedIndexDef{
       ShardBuckets: $6.expr(),
     }
   }
+  |
+  USING HASH
+  {
+    $$.val = &tree.ShardedIndexDef{
+      ShardBuckets: tree.DefaultVal{},
+    }
+  }
   | /* EMPTY */
   {
     $$.val = (*tree.ShardedIndexDef)(nil)