rdbms: Remove references to pg_attrdef.adsrc in Postgres code

PostgreSQL v12 will remove the long-deprecated column
pg_attrdef.adsrc.  The supported way to introspect into column
default values is pg_get_expr(adbin, adrelid), which works
back through all versions of PostgreSQL supported by wikimedia.

Changing to the supported method will allow the upcoming v12 of the
database to be used while maintaining compatibility with older
versions, without needing to write version-specific code.

This patch has been tested with maintenance/update.php and
with phpunit in PostgreSQL versions 9.2, 11, and 12dev.  It does
not harm the first two, and fixes errors that would otherwise
arise in the dev version.  All unit tests which pass under version
11 now pass under 12dev as well.

Bug: T237931
Change-Id: I874d347fd286b26773113d4f0c6c30d9a4055ad3
(cherry picked from commit 27d342ef4bd31da48b0e10655daf1320e3d00b50)

diff --git a/includes/libs/rdbms/database/DatabasePostgres.php b/includes/libs/rdbms/database/DatabasePostgres.php
index 94509a3..299eb3c 100644 (file)
--- a/includes/libs/rdbms/database/DatabasePostgres.php
+++ b/includes/libs/rdbms/database/DatabasePostgres.php
@@ -816,7 +816,7 @@ __INDEXATTR__;
                        . ' WHERE relkind = \'r\''
                        . ' AND nspname = ' . $this->addQuotes( $this->getCoreSchema() )
                        . ' AND relname = ' . $this->addQuotes( $oldName )
-                       . ' AND adsrc LIKE \'nextval(%\'',
+                       . ' AND pg_get_expr(adbin, adrelid) LIKE \'nextval(%\'',
                        $fname
                );
                $row = $this->fetchObject( $res );
@@ -851,10 +851,10 @@ __INDEXATTR__;
                        }
 
                        $oid = $this->fetchObject( $res )->oid;
-                       $res = $this->query( 'SELECT adsrc FROM pg_attribute a'
+                       $res = $this->query( 'SELECT pg_get_expr(adbin, adrelid) AS adsrc FROM pg_attribute a'
                                . ' JOIN pg_attrdef d ON (a.attrelid=d.adrelid and a.attnum=d.adnum)'
                                . " WHERE a.attrelid = $oid"
-                               . ' AND adsrc LIKE \'nextval(%\'',
+                               . ' AND pg_get_expr(adbin, adrelid) LIKE \'nextval(%\'',
                                $fname
                        );
                        $row = $this->fetchObject( $res );

diff --git a/includes/libs/rdbms/field/PostgresField.php b/includes/libs/rdbms/field/PostgresField.php
index 53c3d33..7596a3b 100644 (file)
--- a/includes/libs/rdbms/field/PostgresField.php
+++ b/includes/libs/rdbms/field/PostgresField.php
@@ -17,7 +17,7 @@ class PostgresField implements Field {
 SELECT
  attnotnull, attlen, conname AS conname,
  atthasdef,
- adsrc,
+ pg_get_expr(adbin, adrelid) AS adsrc,
  COALESCE(condeferred, 'f') AS deferred,
  COALESCE(condeferrable, 'f') AS deferrable,
  CASE WHEN typname = 'int2' THEN 'smallint'