If XLOG_DBASE_CREATE_FILE_COPY occurs between an incremental backup and its reference backup, every relation whose DB OID and tablespace OID match the corresponding values in that record should be backed up in full. Currently that's not happening, because the WAL summarizer doesn't see the XLOG_DBASE_CREATE_FILE_COPY as referencing any particular relfilenode and so basically ignores it. The same happens for XLOG_DBASE_CREATE_WAL_LOG, but that case is OK because that only covers creating the directory itself, not anything underneath it, and there will be separate WAL records telling us the relfilenodes created below the new directory and the pages modified therein.
AFAICS, fixing this requires some way of noting in the WAL summary file that an entire directory got blown away. I chose to do that by setting the limit block to 0 for a fake relation with the given DB OID and TS OID and relfilenumber 0, which seems natural. Patch with test case attached. The test case in brief is: initdb -c summarize_wal=on # start the server in $PGDATA psql -c 'create database lakh oid = 100000 strategy = file_copy' postgres psql -c 'create table t1 (a int)' lakh pg_basebackup -cfast -Dt1 dropdb lakh psql -c 'create database lakh oid = 100000 strategy = file_copy' postgres pg_basebackup -cfast -Dt2 --incremental t1/backup_manifest pg_combinebackup t1 t2 -o result # stop the server, restart from the result directory psql -c 'select * from t1' lakh Without this patch, you get something like: ERROR: could not open file "base/100000/16388": No such file or directory ...because the catalog entries from before the database is dropped and recreated manage to end up in pg_combinebackup's output directory, which they should not. With the patch, you correctly get an error about t1 not existing. I thought about whether there were any other WAL records that have similar problems to XLOG_DBASE_CREATE_FILE_COPY and didn't come up with anything. If anyone knows of any similar cases, please let me know. Thanks, -- Robert Haas EDB: http://www.enterprisedb.com
v1-0001-Fix-incremental-backup-interaction-with-XLOG_DBAS.patch
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