sql: improve SHOW TABLES to show row count

This change adds column "estimated_row_count" into result of the "SHOW TABLES"
to show estimated (not real) number of rows.

Besides that the body of the `delegator.delegateShowTables` was a bit
simplified (we do not need two almost similar versions of the query) and
new virtual table `crdb_internal.table_row_statistics` was added (to
show stats for non-root users).

Release note (sql change): This change modifies SHOW TABLES to return
estimates number of rows.

pkg/cli/zip.go

@@ -76,6 +76,7 @@ var debugZipTablesPerCluster = []string{
  "crdb_internal.schema_changes",
  "crdb_internal.partitions",
  "crdb_internal.zones",
+ "crdb_internal.table_row_statistics",
 }
 
 // Tables collected from each node in a debug zip.

pkg/server/admin.go

@@ -327,7 +327,7 @@ func (s *adminServer) DatabaseDetails(
  // Marshal table names.
  {
  scanner := makeResultScanner(cols)
- if a, e := len(cols), 3; a != e {
+ if a, e := len(cols), 4; a != e {
  return nil, s.serverErrorf("show tables columns mismatch: %d != expected %d", a, e)
  }
  for _, row := range rows {

pkg/sql/crdb_internal.go

@@ -106,6 +106,7 @@ var crdbInternal = virtualSchema{
  sqlbase.CrdbInternalTableColumnsTableID: crdbInternalTableColumnsTable,
  sqlbase.CrdbInternalTableIndexesTableID: crdbInternalTableIndexesTable,
  sqlbase.CrdbInternalTablesTableID: crdbInternalTablesTable,
+ sqlbase.CrdbInternalTablesTableLastStatsID: crdbInternalTablesTableLastStats,
  sqlbase.CrdbInternalTxnStatsTableID: crdbInternalTxnStatsTable,
  sqlbase.CrdbInternalZonesTableID: crdbInternalZonesTable,
  },
@@ -337,6 +338,59 @@ CREATE TABLE crdb_internal.tables (
  },
 }
 
+var crdbInternalTablesTableLastStats = virtualSchemaTable{
+ comment: "the latest stats for all tables accessible by current user in current database (KV scan)",
+ schema: `
+CREATE TABLE crdb_internal.table_row_statistics (
+ table_id INT NOT NULL,
+ table_name STRING NOT NULL,
+ estimated_row_count INT NOT NULL
+)`,
+ populate: func(ctx context.Context, p *planner, db *sqlbase.ImmutableDatabaseDescriptor, addRow func(...tree.Datum) error) error {
+ // Collect the latests statistics for all tables.
+ query := `` +
+ `SELECT s."tableID", max(s."rowCount")` +
+ ` FROM system.table_statistics AS s ` +
+ ` JOIN (` +
+ ` SELECT "tableID", MAX("createdAt") AS last_dt ` +
+ ` FROM system.table_statistics ` +
+ ` GROUP BY "tableID"` +
+ ` ) AS l ON l."tableID" = s."tableID" ` +
+ ` AND l.last_dt = s."createdAt"` +
+ ` GROUP BY s."tableID"`
+ statRows, err := p.ExtendedEvalContext().ExecCfg.InternalExecutor.QueryEx(
+ ctx, "crdb-internal-statistics-table", p.txn,
+ sqlbase.InternalExecutorSessionDataOverride{User: security.RootUser},
+ query)
+ if err != nil {
+ return err
+ }
+
+ // Convert statistics into map: tableID -> rowCount.
+ statMap := make(map[tree.DInt]tree.DInt)
+ for _, r := range statRows {
+ statMap[tree.MustBeDInt(r[0])] = tree.MustBeDInt(r[1])
+ }
+
+ // Walk over all available tables and show row count for each of them
+ // using collected statistics.
+ return forEachTableDescAll(ctx, p, db, virtualMany,
+ func(db *sqlbase.ImmutableDatabaseDescriptor, _ string, table *ImmutableTableDescriptor) error {
+ tableID := tree.DInt(table.ID)
+ rowCount := tree.DInt(0)
+ if cnt, ok := statMap[tableID]; ok {
+ rowCount = cnt
+ }
+ return addRow(
+ tree.NewDInt(tableID),
+ tree.NewDString(table.Name),
+ &rowCount,
+ )
+ },
+ )
+ },
+}
+
 // TODO(tbg): prefix with kv_.
 var crdbInternalSchemaChangesTable = virtualSchemaTable{
  comment: `ongoing schema changes, across all descriptors accessible by current user (KV scan; expensive!)`,

pkg/sql/delegate/show_tables.go

@@ -43,53 +43,37 @@ func (d *delegator) delegateShowTables(n *tree.ShowTables) (tree.Statement, erro
  schemaClause = "AND ns.nspname NOT IN ('information_schema', 'pg_catalog', 'crdb_internal', 'pg_extension')"
  }
 
- var query string
- if n.WithComment {
- const getTablesQuery = `
-SELECT
- ns.nspname AS schema_name,
- pc.relname AS table_name,
- (CASE
- WHEN pc.relkind = 'v' THEN 'view'
- WHEN pc.relkind = 'S' THEN 'sequence'
- ELSE 'table'
- END) AS "type",
- COALESCE(pd.description, '') AS comment
- FROM %[1]s.pg_catalog.pg_class AS pc
- JOIN %[1]s.pg_catalog.pg_namespace AS ns ON (ns.oid = pc.relnamespace)
- LEFT JOIN %[1]s.pg_catalog.pg_description AS pd ON (pc.oid = pd.objoid AND pd.objsubid = 0)
-WHERE pc.relkind IN ('r', 'v', 'S') %[2]s
-ORDER BY schema_name, table_name
-`
-
- query = fmt.Sprintf(
- getTablesQuery,
- &name.CatalogName,
- schemaClause,
- )
-
- } else {
- const getTablesQuery = `
-SELECT
- ns.nspname AS schema_name,
- pc.relname AS table_name,
- (CASE
- WHEN pc.relkind = 'v' THEN 'view'
- WHEN pc.relkind = 'S' THEN 'sequence'
- ELSE 'table'
- END) AS "type"
- FROM %[1]s.pg_catalog.pg_class AS pc
- JOIN %[1]s.pg_catalog.pg_namespace AS ns ON (ns.oid = pc.relnamespace)
-WHERE pc.relkind IN ('r', 'v', 'S') %[2]s
-ORDER BY schema_name, table_name
+ const getTablesQuery = `
+SELECT ns.nspname AS schema_name
+ , pc.relname AS table_name
+ , CASE
+ WHEN pc.relkind = 'v' THEN 'view'
+ WHEN pc.relkind = 'S' THEN 'sequence'
+ ELSE 'table'
+ END AS type
+ , (
+ SELECT estimated_row_count
+ FROM crdb_internal.table_row_statistics
+ WHERE table_id = pc.oid::int
+ ) AS estimated_row_count
+ %[3]s
+ FROM %[1]s.pg_catalog.pg_class AS pc
+ JOIN %[1]s.pg_catalog.pg_namespace AS ns ON (ns.oid = pc.relnamespace)
+ LEFT
+ JOIN %[1]s.pg_catalog.pg_description AS pd ON (pc.oid = pd.objoid AND pd.objsubid = 0)
+ WHERE pc.relkind IN ('r', 'v', 'S')
+ %[2]s
+ ORDER BY schema_name, table_name
 `
-
- query = fmt.Sprintf(
- getTablesQuery,
- &name.CatalogName,
- schemaClause,
- )
+ var comment string
+ if n.WithComment {
+ comment = `, COALESCE(pd.description, '') AS "comment"`
  }
-
+ query := fmt.Sprintf(
+ getTablesQuery,
+ &name.CatalogName,
+ schemaClause,
+ comment,
+ )
  return parse(query)
 }

pkg/sql/logictest/testdata/logic_test/alter_table_mixed_19.2_20.1

@@ -36,10 +36,10 @@ DROP TABLE t
 statement error schema change cannot be initiated in this version until the version upgrade is finalized
 TRUNCATE TABLE t
 
-query TTT
+query TTTI
 SHOW TABLES
 ----
-public t table
+public t table 0
 
 subtest columns
 
@@ -143,10 +143,10 @@ CREATE TABLE db.t (a INT)
 statement error schema change cannot be initiated in this version until the version upgrade is finalized
 DROP DATABASE db
 
-query TTT
+query TTTI
 SHOW TABLES FROM db
 ----
-public t table
+public t table NULL
 
 subtest non_backfill_schema_changes
 

pkg/sql/logictest/testdata/logic_test/crdb_internal

@@ -8,48 +8,49 @@ CREATE TABLE crdb_internal.t (x INT)
 query error database "crdb_internal" does not exist
 DROP DATABASE crdb_internal
 
-query TTT
+query TTTI
 SHOW TABLES FROM crdb_internal
 ----
-crdb_internal backward_dependencies table
-crdb_internal builtin_functions table
-crdb_internal cluster_queries table
-crdb_internal cluster_sessions table
-crdb_internal cluster_settings table
-crdb_internal cluster_transactions table
-crdb_internal create_statements table
-crdb_internal create_type_statements table
-crdb_internal databases table
-crdb_internal feature_usage table
-crdb_internal forward_dependencies table
-crdb_internal gossip_alerts table
-crdb_internal gossip_liveness table
-crdb_internal gossip_network table
-crdb_internal gossip_nodes table
-crdb_internal index_columns table
-crdb_internal jobs table
-crdb_internal kv_node_status table
-crdb_internal kv_store_status table
-crdb_internal leases table
-crdb_internal node_build_info table
-crdb_internal node_metrics table
-crdb_internal node_queries table
-crdb_internal node_runtime_info table
-crdb_internal node_sessions table
-crdb_internal node_statement_statistics table
-crdb_internal node_transactions table
-crdb_internal node_txn_stats table
-crdb_internal partitions table
-crdb_internal predefined_comments table
-crdb_internal ranges view
-crdb_internal ranges_no_leases table
-crdb_internal schema_changes table
-crdb_internal session_trace table
-crdb_internal session_variables table
-crdb_internal table_columns table
-crdb_internal table_indexes table
-crdb_internal tables table
-crdb_internal zones table
+crdb_internal backward_dependencies table 0
+crdb_internal builtin_functions table 0
+crdb_internal cluster_queries table 0
+crdb_internal cluster_sessions table 0
+crdb_internal cluster_settings table 0
+crdb_internal cluster_transactions table 0
+crdb_internal create_statements table 0
+crdb_internal create_type_statements table 0
+crdb_internal databases table 0
+crdb_internal feature_usage table 0
+crdb_internal forward_dependencies table 0
+crdb_internal gossip_alerts table 0
+crdb_internal gossip_liveness table 0
+crdb_internal gossip_network table 0
+crdb_internal gossip_nodes table 0
+crdb_internal index_columns table 0
+crdb_internal jobs table 0
+crdb_internal kv_node_status table 0
+crdb_internal kv_store_status table 0
+crdb_internal leases table 0
+crdb_internal node_build_info table 0
+crdb_internal node_metrics table 0
+crdb_internal node_queries table 0
+crdb_internal node_runtime_info table 0
+crdb_internal node_sessions table 0
+crdb_internal node_statement_statistics table 0
+crdb_internal node_transactions table 0
+crdb_internal node_txn_stats table 0
+crdb_internal partitions table 0
+crdb_internal predefined_comments table 0
+crdb_internal ranges view 0
+crdb_internal ranges_no_leases table 0
+crdb_internal schema_changes table 0
+crdb_internal session_trace table 0
+crdb_internal session_variables table 0
+crdb_internal table_columns table 0
+crdb_internal table_indexes table 0
+crdb_internal table_row_statistics table 0
+crdb_internal tables table 0
+crdb_internal zones table 0
 
 statement ok
 CREATE DATABASE testdb; CREATE TABLE testdb.foo(x INT)

pkg/sql/logictest/testdata/logic_test/drop_index

@@ -170,12 +170,12 @@ users foo true 2 id ASC false
 statement ok
 CREATE VIEW v2 AS SELECT name FROM v
 
-query TTT
+query TTTI
 SHOW TABLES
 ----
-public users table
-public v view
-public v2 view
+public users table 0
+public v view 0
+public v2 view 0 
 
 statement ok
 GRANT ALL ON users to testuser
@@ -199,10 +199,10 @@ SHOW INDEXES FROM users
 table_name index_name non_unique seq_in_index column_name direction storing implicit
 users primary false 1 id ASC false false
 
-query TTT
+query TTTI
 SHOW TABLES
 ----
-public users table
+public users table 0
 
 # Test the syntax without a '@'
 

pkg/sql/logictest/testdata/logic_test/drop_table

@@ -6,11 +6,11 @@ CREATE TABLE a (id INT PRIMARY KEY)
 statement ok
 CREATE TABLE b (id INT PRIMARY KEY)
 
-query TTT
+query TTTI
 SHOW TABLES FROM test
 ----
-public a table
-public b table
+public a table 0
+public b table 0
 
 statement ok
 INSERT INTO a VALUES (3),(7),(2)
@@ -35,10 +35,10 @@ SELECT job_type, status FROM [SHOW JOBS] WHERE job_type = 'SCHEMA CHANGE GC' OR
 SCHEMA CHANGE succeeded
 SCHEMA CHANGE GC running
 
-query TTT
+query TTTI
 SHOW TABLES FROM test
 ----
-public b table
+public b table 0
 
 statement error pgcode 42P01 relation "a" does not exist
 SELECT * FROM a