We have an optimization to bulkload date in pg_restore, but the code
only works in parallel restore (--jobs >= 2). Why don't we do the
same optimization in the serial restore (--jobs = 1) ?
We checks is_parallel to decide to use BEGIN-TRUNCATE-COPY: if (is_parallel && te->created)
but we can always do it unless --single-transaction, right? if (!ropt->single_txn && te->created)
[ in restore_toc_entry() ]
/** In parallel restore, if we created the table earlier in* the run then we wrap the COPY in a transaction and*
precedeit with a TRUNCATE. If archiving is not on* this prevents WAL-logging the COPY. This obtains a* speedup similar
tothat from using single_txn mode in* non-parallel restores.*/
if (is_parallel && te->created) <==== HERE
{ /* * Parallel restore is always talking directly to a * server, so no need to see if we should issue BEGIN.
*/ StartTransaction(AH);
/* * If the server version is >= 8.4, make sure we issue * TRUNCATE with ONLY so that child tables are not
*wiped. */ ahprintf(AH, "TRUNCATE TABLE %s%s;\n\n", (PQserverVersion(AH->connection) >= 80400 ?
"ONLY " : ""), fmtId(te->tag));
}
Regards,
---
Takahiro Itagaki
NTT Open Source Software Center
