On Wed, Feb 04, 2026 at 10:06:29AM -0600, Nathan Bossart wrote: > IIUC your critique is that this doesn't explain the overwriting behavior > like the older comment does. I'll work on adding that. > > [...] > > I'm considering a couple of options here, but it seems like the easiest > thing to do is to move the TRUNCATE commands to the end of the dump file. > At least, that seems to be sufficient for our existing tests. If that > seems okay to you, I can work on putting together a patch.
Here is a rough first draft of a patch that does this. -- nathan
>From c911f5b16132514a461f72b550ee8cd86dfadc1d Mon Sep 17 00:00:00 2001 From: Nathan Bossart <[email protected]> Date: Wed, 4 Feb 2026 14:04:18 -0600 Subject: [PATCH v1 1/1] fix pg_largeobject_metadata file transfer --- src/bin/pg_dump/pg_dump.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c index 2bebefd0ba2..3ba57492fa6 100644 --- a/src/bin/pg_dump/pg_dump.c +++ b/src/bin/pg_dump/pg_dump.c @@ -379,6 +379,7 @@ static const char *getFormattedTypeName(Archive *fout, Oid oid, OidOptions opts) static void getLOs(Archive *fout); static void dumpLO(Archive *fout, const LoInfo *loinfo); static int dumpLOs(Archive *fout, const void *arg); +static void dumpLOTruncation(Archive *fout); static void dumpPolicy(Archive *fout, const PolicyInfo *polinfo); static void dumpPublication(Archive *fout, const PublicationInfo *pubinfo); static void dumpPublicationTable(Archive *fout, const PublicationRelInfo *pubrinfo); @@ -1157,7 +1158,10 @@ main(int argc, char **argv) * subsequent COMMENT and SECURITY LABEL commands work. pg_upgrade * can't copy/link the files from older versions because aclitem * (needed by pg_largeobject_metadata.lomacl) changed its storage - * format in v16. + * format in v16. At the end of the dump, we'll generate a TRUNCATE + * command for pg_largeobject_metadata so that it's contents are + * cleared in preparation for the subsequent file transfer by + * pg_upgrade. */ if (fout->remoteVersion >= 160000) lo_metadata->dataObj->filtercond = "WHERE oid IN " @@ -1243,6 +1247,13 @@ main(int argc, char **argv) for (i = 0; i < numObjs; i++) dumpDumpableObject(fout, dobjs[i]); + /* + * For binary upgrades, set relfrozenxids, relminmxids, and relfilenodes + * of pg_largeobject and maybe pg_largeobject_metadata, and remove all + * their files. We will transfer them from the old cluster as needed. + */ + dumpLOTruncation(fout); + /* * Set up options info to ensure we dump what we want. */ @@ -3671,6 +3682,20 @@ dumpDatabase(Archive *fout) .dropStmt = delQry->data, .deps = &dbDumpId)); + PQclear(res); + + free(qdatname); + destroyPQExpBuffer(dbQry); + destroyPQExpBuffer(delQry); + destroyPQExpBuffer(creaQry); + destroyPQExpBuffer(labelq); +} + +static void +dumpLOTruncation(Archive *fout) +{ + DumpOptions *dopt = fout->dopt; + /* * pg_largeobject comes from the old system intact, so set its * relfrozenxids, relminmxids and relfilenode. @@ -3769,14 +3794,14 @@ dumpDatabase(Archive *fout) ArchiveEntry(fout, nilCatalogId, createDumpId(), ARCHIVE_OPTS(.tag = "pg_largeobject", .description = "pg_largeobject", - .section = SECTION_PRE_DATA, + .section = SECTION_POST_DATA, .createStmt = loOutQry->data)); if (fout->remoteVersion >= 160000) ArchiveEntry(fout, nilCatalogId, createDumpId(), ARCHIVE_OPTS(.tag = "pg_largeobject_metadata", .description = "pg_largeobject_metadata", - .section = SECTION_PRE_DATA, + .section = SECTION_POST_DATA, .createStmt = lomOutQry->data)); PQclear(lo_res); @@ -3787,14 +3812,6 @@ dumpDatabase(Archive *fout) destroyPQExpBuffer(loOutQry); destroyPQExpBuffer(lomOutQry); } - - PQclear(res); - - free(qdatname); - destroyPQExpBuffer(dbQry); - destroyPQExpBuffer(delQry); - destroyPQExpBuffer(creaQry); - destroyPQExpBuffer(labelq); } /* -- 2.50.1 (Apple Git-155)
