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Track statistics for spilling of changes from ReorderBuffer.

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This adds the statistics about transactions spilled to disk from
ReorderBuffer. Users can query the pg_stat_replication_slots view to check
these stats and call pg_stat_reset_replication_slot to reset the stats of
a particular slot. Users can pass NULL in pg_stat_reset_replication_slot
to reset stats of all the slots.

This commit extends the statistics collector to track this information
about slots.

Author: Sawada Masahiko and Amit Kapila
Reviewed-by: Amit Kapila and Dilip Kumar
Discussion: https://postgr.es/m/CA+fd4k5_pPAYRTDrO2PbtTOe0eHQpBvuqmCr8ic39uTNmR49Eg@mail.gmail.com
This commit is contained in:
Amit Kapila
2020-10-08 09:09:08 +05:30
parent 8d2a01ae12
commit 9868167500
16 changed files with 700 additions and 8 deletions
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22
src/backend/replication/logical/reorderbuffer.c
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@ -343,6 +343,10 @@ ReorderBufferAllocate(void)
buffer->outbufsize = 0;
buffer->size = 0;
buffer->spillTxns = 0;
buffer->spillCount = 0;
buffer->spillBytes = 0;
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
dlist_init(&buffer->toplevel_by_lsn);
@ -1579,6 +1583,13 @@ ReorderBufferTruncateTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
ReorderBufferRestoreCleanup(rb, txn);
txn->txn_flags &= ~RBTXN_IS_SERIALIZED;
/*
* We set this flag to indicate if the transaction is ever serialized.
* We need this to accurately update the stats as otherwise the same
* transaction can be counted as serialized multiple times.
*/
txn->txn_flags |= RBTXN_IS_SERIALIZED_CLEAR;
}
/* also reset the number of entries in the transaction */
@ -3112,6 +3123,7 @@ ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
int fd = -1;
XLogSegNo curOpenSegNo = 0;
Size spilled = 0;
Size size = txn->size;
elog(DEBUG2, "spill %u changes in XID %u to disk",
(uint32) txn->nentries_mem, txn->xid);
@ -3170,6 +3182,16 @@ ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
spilled++;
}
/* update the statistics iff we have spilled anything */
if (spilled)
{
rb->spillCount += 1;
rb->spillBytes += size;
/* don't consider already serialized transactions */
rb->spillTxns += (rbtxn_is_serialized(txn) || rbtxn_is_serialized_clear(txn)) ? 0 : 1;
}
Assert(spilled == txn->nentries_mem);
Assert(dlist_is_empty(&txn->changes));
txn->nentries_mem = 0;