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BUG #17465: Wrong error message while trying to change system column type. 2+ messages / 2 participants [nested] [flat]
* BUG #17465: Wrong error message while trying to change system column type. @ 2022-04-18 11:13 PG Bug reporting form <noreply@postgresql.org> 2022-04-18 15:36 ` Re: BUG #17465: Wrong error message while trying to change system column type. Tom Lane <tgl@sss.pgh.pa.us> 0 siblings, 1 reply; 2+ messages in thread From: PG Bug reporting form @ 2022-04-18 11:13 UTC (permalink / raw) To: pgsql-bugs@lists.postgresql.org; +Cc: r.zharkov@postgrespro.ru The following bug has been logged on the website: Bug reference: 17465 Logged by: Roman Zharkov Email address: r.zharkov@postgrespro.ru PostgreSQL version: 13.4 Operating system: Windows Description: Hello, accidentally I tried to change a system column data type on Windows and got a strange error message "no owned sequence found": psql (15devel) postgres=# alter table t1 alter column cmin type text; ERROR: no owned sequence found postgres=# alter table t1 alter column cmax type text; ERROR: cannot alter system column "cmax" This happens due incorrect checking for negative attnum: if (TupleDescAttr(tupdesc, attnum - 1)->attidentity) ( line https://github.com/postgres/postgres/blob/1a8b110539efe18803c1fa8aa452a2178dbad9a9/src/backend/parse... ) I think the ATParseTransformCmd() function needs the same check as the check in the ATPrepAlterColumnType() function. diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 2cd8546d471..0034a06ea71 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -4630,10 +4630,11 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd, case AT_AlterColumnType: /* ALTER COLUMN TYPE */ ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_COMPOSITE_TYPE | ATT_FOREIGN_TABLE); + + Assert(cmd != NULL); /* See comments for ATPrepAlterColumnType */ cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, recurse, lockmode, AT_PASS_UNSET, context); - Assert(cmd != NULL); /* Performs own recursion */ ATPrepAlterColumnType(wqueue, tab, rel, recurse, recursing, cmd, lockmode, context); @@ -5250,6 +5251,26 @@ ATParseTransformCmd(List **wqueue, AlteredTableInfo *tab, Relation rel, List *beforeStmts; List *afterStmts; ListCell *lc; + char *colName = cmd->name; + HeapTuple tuple; + Form_pg_attribute attTup; + AttrNumber attnum; + + tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_COLUMN), + errmsg("column \"%s\" of relation \"%s\" does not exist", + colName, RelationGetRelationName(rel)))); + attTup = (Form_pg_attribute)GETSTRUCT(tuple); + attnum = attTup->attnum; + + /* Can't alter a system attribute */ + if (attnum <= 0) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot alter system column \"%s\"", + colName))); /* Gin up an AlterTableStmt with just this subcommand and this table */ atstmt->relation = ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: BUG #17465: Wrong error message while trying to change system column type. 2022-04-18 11:13 BUG #17465: Wrong error message while trying to change system column type. PG Bug reporting form <noreply@postgresql.org> @ 2022-04-18 15:36 ` Tom Lane <tgl@sss.pgh.pa.us> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2022-04-18 15:36 UTC (permalink / raw) To: r.zharkov@postgrespro.ru; +Cc: pgsql-bugs@lists.postgresql.org PG Bug reporting form <noreply@postgresql.org> writes: > accidentally I tried to change a system column data type on Windows and got > a strange error message "no owned sequence found": > postgres=# alter table t1 alter column cmin type text; > ERROR: no owned sequence found > postgres=# alter table t1 alter column cmax type text; > ERROR: cannot alter system column "cmax" Yeah, same here. > I think the ATParseTransformCmd() function needs the same check as the check > in the ATPrepAlterColumnType() function. That seems pretty duplicative. I think it's sufficient to do something like - if (TupleDescAttr(tupdesc, attnum - 1)->attidentity) + if (attnum > 0 && + TupleDescAttr(tupdesc, attnum - 1)->attidentity) in the faulty code, and let the actual error message come out where it does now. Will fix, thanks for the report! regards, tom lane ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2022-04-18 15:36 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2022-04-18 11:13 BUG #17465: Wrong error message while trying to change system column type. PG Bug reporting form <noreply@postgresql.org> 2022-04-18 15:36 ` Tom Lane <tgl@sss.pgh.pa.us>
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