Fix pg_dump --clean with partitioned indexes.

We'd try to drop the partitions of a partitioned index separately,
which is disallowed by the backend, leading to an error during
restore.  While the error is harmless, it causes problems if you
try to use --single-transaction mode.

Fortunately, there seems no need to do a DROP at all, since the
partition will go away silently when we drop either the parent index
or the partition's table.  So just make the DROP conditional on not
being a partition.

Reported-by: jian he <jian.universality@gmail.com>
Author: jian he <jian.universality@gmail.com>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CACJufxF0QSdkjFKF4di-JGWN6CSdQYEAhGPmQJJCdkSZtd=oLg@mail.gmail.com
Backpatch-through: 13

diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index ba71c0b0f3246b67be45acb3f1b6be54d8432031..2001d28b49fbad9254ecfb362500ee240486015b 100644 (file)
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -16558,7 +16558,17 @@ dumpIndex(Archive *fout, const IndxInfo *indxinfo)
                                                          qindxname);
                }
 
-               appendPQExpBuffer(delq, "DROP INDEX %s;\n", qqindxname);
+               /*
+                * If this index is a member of a partitioned index, the backend will
+                * not allow us to drop it separately, so don't try.  It will go away
+                * automatically when we drop either the index's table or the
+                * partitioned index.  (If, in a selective restore with --clean, we
+                * drop neither of those, then this index will not be dropped either.
+                * But that's fine, and even if you think it's not, the backend won't
+                * let us do differently.)
+                */
+               if (indxinfo->parentidx == 0)
+                       appendPQExpBuffer(delq, "DROP INDEX %s;\n", qqindxname);
 
                if (indxinfo->dobj.dump & DUMP_COMPONENT_DEFINITION)
                        ArchiveEntry(fout, indxinfo->dobj.catId, indxinfo->dobj.dumpId,
@@ -16611,11 +16621,15 @@ dumpIndexAttach(Archive *fout, const IndexAttachInfo *attachinfo)
                                                  fmtQualifiedDumpable(attachinfo->partitionIdx));
 
                /*
-                * There is no point in creating a drop query as the drop is done by
-                * index drop.  (If you think to change this, see also
-                * _printTocEntry().)  Although this object doesn't really have
-                * ownership as such, set the owner field anyway to ensure that the
-                * command is run by the correct role at restore time.
+                * There is no need for a dropStmt since the drop is done implicitly
+                * when we drop either the index's table or the partitioned index.
+                * Moreover, since there's no ALTER INDEX DETACH PARTITION command,
+                * there's no way to do it anyway.  (If you think to change this,
+                * consider also what to do with --if-exists.)
+                *
+                * Although this object doesn't really have ownership as such, set the
+                * owner field anyway to ensure that the command is run by the correct
+                * role at restore time.
                 */
                ArchiveEntry(fout, attachinfo->dobj.catId, attachinfo->dobj.dumpId,
                                         ARCHIVE_OPTS(.tag = attachinfo->dobj.name,