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Don't build full initial logical decoding snapshot if NOEXPORT_SNAPSHOT.

Earlier commits (56e19d938dd14 and 2bef06d5164) make it cheaper to
create a logical slot if not exporting the initial snapshot.  If
NOEXPORT_SNAPSHOT is specified, we can skip the overhead, not just
when creating a slot via sql (which can't export snapshots).  As
NOEXPORT_SNAPSHOT has only recently been introduced, this shouldn't be
backpatched.
This commit is contained in:
Andres Freund 2017-04-27 15:49:22 -07:00
parent 56e19d938d
commit ab9c43381e

View File

@ -873,6 +873,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
if (cmd->kind == REPLICATION_KIND_LOGICAL)
{
LogicalDecodingContext *ctx;
bool need_full_snapshot = false;
/*
* Do options check early so that we can bail before calling the
@ -884,6 +885,8 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
ereport(ERROR,
(errmsg("CREATE_REPLICATION_SLOT ... EXPORT_SNAPSHOT "
"must not be called inside a transaction")));
need_full_snapshot = true;
}
else if (snapshot_action == CRS_USE_SNAPSHOT)
{
@ -906,10 +909,11 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
ereport(ERROR,
(errmsg("CREATE_REPLICATION_SLOT ... USE_SNAPSHOT "
"must not be called in a subtransaction")));
need_full_snapshot = true;
}
ctx = CreateInitDecodingContext(cmd->plugin, NIL,
true, /* build snapshot */
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
logical_read_xlog_page,
WalSndPrepareWrite, WalSndWriteData);