Merge #68245

68245: sql implement the pg_db_role_setting table r=RichardJCai a=rafiss

touches #21151

Release note (sql change): The pg_db_role_setting table of the
pg_catalog is now implemented. When `ALTER ROLE ... SET var`
is used to configure per-role defaults, these default settings will be
populated in pg_db_role_setting. This table contains the same data no
matter which database the current session is using.

See https://www.postgresql.org/docs/13/catalog-pg-db-role-setting.html

Co-authored-by: Rafi Shamim <[email protected]>

pkg/sql/logictest/testdata/logic_test/alter_role_set

@@ -22,6 +22,20 @@ database_id  role_name      settings
 53           ·              {application_name=c}
 53           test_set_role  {application_name=b}
 
+# Defaults should be in pg_catalog too.
+query OOTTT colnames
+SELECT setdatabase, setrole, d.datname, r.rolname, setconfig
+FROM pg_catalog.pg_db_role_setting
+LEFT JOIN pg_catalog.pg_database d ON setdatabase = d.oid
+LEFT JOIN pg_catalog.pg_roles r ON setrole = r.oid
+ORDER BY 1, 2
+----
+setdatabase  setrole    datname      rolname        setconfig
+0            0          NULL         NULL           {application_name=d}
+0            265380634  NULL         test_set_role  {application_name=a}
+53           0          test_set_db  NULL           {application_name=c}
+53           265380634  test_set_db  test_set_role  {application_name=b}
+
 statement ok
 ALTER ROLE test_set_role SET backslash_quote = 'safe_encoding'
 

pkg/sql/logictest/testdata/logic_test/pg_catalog

@@ -3642,7 +3642,7 @@ objoid      classoid    objsubid  description
 4294967133  4294967137  0         encoding conversions (empty - unimplemented)
 4294967132  4294967137  0         pg_cursors was created for compatibility and is currently unimplemented
 4294967131  4294967137  0         available databases (incomplete)
-4294967130  4294967137  0         pg_db_role_setting was created for compatibility and is currently unimplemented
+4294967130  4294967137  0         contains the default values that have been configured for session variables
 4294967129  4294967137  0         default ACLs; these are the privileges that will be assigned to newly created objects
 4294967128  4294967137  0         dependency relationships (incomplete)
 4294967127  4294967137  0         object comments

pkg/sql/pg_catalog.go

@@ -37,6 +37,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/privilege"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/builtins"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+	"github.com/cockroachdb/cockroach/pkg/sql/sessiondata"
 	"github.com/cockroachdb/cockroach/pkg/sql/sqlerrors"
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
 	"github.com/cockroachdb/cockroach/pkg/sql/vtable"
@@ -2835,12 +2836,39 @@ var pgCatalogShmemAllocationsTable = virtualSchemaTable{
 }
 
 var pgCatalogDbRoleSettingTable = virtualSchemaTable{
-	comment: "pg_db_role_setting was created for compatibility and is currently unimplemented",
-	schema:  vtable.PgCatalogDbRoleSetting,
-	populate: func(ctx context.Context, p *planner, _ catalog.DatabaseDescriptor, addRow func(...tree.Datum) error) error {
+	comment: `contains the default values that have been configured for session variables
+https://www.postgresql.org/docs/13/catalog-pg-db-role-setting.html`,
+	schema: vtable.PgCatalogDbRoleSetting,
+	populate: func(ctx context.Context, p *planner, _ catalog.DatabaseDescriptor, addRow func(...tree.Datum) error) error {
+		rows, err := p.extendedEvalCtx.ExecCfg.InternalExecutor.QueryBufferedEx(
+			ctx,
+			"select-db-role-settings",
+			p.EvalContext().Txn,
+			sessiondata.InternalExecutorOverride{User: security.RootUserName()},
+			`SELECT database_id, role_name, settings FROM system.public.database_role_settings`,
+		)
+		if err != nil {
+			return err
+		}
+		h := makeOidHasher()
+		for _, row := range rows {
+			databaseID := tree.MustBeDOid(row[0])
+			roleName := tree.MustBeDString(row[1])
+			roleID := oidZero
+			if roleName != "" {
+				roleID = h.UserOid(security.MakeSQLUsernameFromPreNormalizedString(string(roleName)))
+			}
+			settings := tree.MustBeDArray(row[2])
+			if err := addRow(
+				settings,
+				databaseID,
+				roleID,
+			); err != nil {
+				return err
+			}
+		}
 		return nil
 	},
-	unimplemented: true,
 }
 
 var pgCatalogTimezoneNamesTable = virtualSchemaTable{

pkg/sql/vtable/pg_catalog.go

@@ -989,8 +989,9 @@ CREATE TABLE pg_catalog.pg_shmem_allocations (
 	allocated_size INT
 )`
 
-// PgCatalogDbRoleSetting is an empty table created by pg_catalog_test
-// and is currently unimplemented.
+// PgCatalogDbRoleSetting contains the default values that have been configured
+// for session variables, for each role and database combination. This table
+// contains the same data no matter which database the current session is using.
 const PgCatalogDbRoleSetting = `
 CREATE TABLE pg_catalog.pg_db_role_setting (
 	setconfig STRING[],