From 7326a7d63801673d3569def65cb7955d6486f254 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Wed, 1 Aug 2018 17:39:07 -0400 Subject: [PATCH] Fix logical replication slot initialization This was broken in commit 9c7d06d60680, which inadvertently gave the wrong value to fast_forward in one StartupDecodingContext call. Fix by flipping the value. Add a test for the obvious error, namely trying to initialize a replication slot with an nonexistent output plugin. While at it, move the CreateDecodingContext call earlier, so that any errors are reported before sending the CopyBoth message. Author: Dave Cramer Reviewed-by: Andres Freund Discussion: https://postgr.es/m/CADK3HHLVkeRe1v4P02-5hj55H3_yJg3AEtpXyEY5T3wuzO2jSg@mail.gmail.com --- contrib/test_decoding/expected/slot.out | 2 ++ contrib/test_decoding/sql/slot.sql | 2 ++ src/backend/replication/logical/logical.c | 2 +- src/backend/replication/walsender.c | 23 +++++++++++++---------- 4 files changed, 18 insertions(+), 11 deletions(-) diff --git a/contrib/test_decoding/expected/slot.out b/contrib/test_decoding/expected/slot.out index 2737a8a301..523621a705 100644 --- a/contrib/test_decoding/expected/slot.out +++ b/contrib/test_decoding/expected/slot.out @@ -30,6 +30,8 @@ SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_t2', 'tes init (1 row) +SELECT pg_create_logical_replication_slot('foo', 'nonexistent'); +ERROR: could not access file "nonexistent": No such file or directory -- here we want to start a new session and wait till old one is gone select pg_backend_pid() as oldpid \gset \c - diff --git a/contrib/test_decoding/sql/slot.sql b/contrib/test_decoding/sql/slot.sql index 24cdf7155d..c8d08f8541 100644 --- a/contrib/test_decoding/sql/slot.sql +++ b/contrib/test_decoding/sql/slot.sql @@ -9,6 +9,8 @@ SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_p', 'test SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot_t2', 'test_decoding', true); +SELECT pg_create_logical_replication_slot('foo', 'nonexistent'); + -- here we want to start a new session and wait till old one is gone select pg_backend_pid() as oldpid \gset \c - diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c index c9bbdcda74..6fc762e318 100644 --- a/src/backend/replication/logical/logical.c +++ b/src/backend/replication/logical/logical.c @@ -312,7 +312,7 @@ CreateInitDecodingContext(char *plugin, ReplicationSlotSave(); ctx = StartupDecodingContext(NIL, InvalidXLogRecPtr, xmin_horizon, - need_full_snapshot, true, + need_full_snapshot, false, read_page, prepare_write, do_write, update_progress); diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index 3a0106bc93..15becc11ee 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -1061,6 +1061,19 @@ StartLogicalReplication(StartReplicationCmd *cmd) got_STOPPING = true; } + /* + * Create our decoding context, making it start at the previously ack'ed + * position. + * + * Do this before sending CopyBoth, so that any errors are reported early. + */ + logical_decoding_ctx = + CreateDecodingContext(cmd->startpoint, cmd->options, false, + logical_read_xlog_page, + WalSndPrepareWrite, WalSndWriteData, + WalSndUpdateProgress); + + WalSndSetState(WALSNDSTATE_CATCHUP); /* Send a CopyBothResponse message, and start streaming */ @@ -1070,16 +1083,6 @@ StartLogicalReplication(StartReplicationCmd *cmd) pq_endmessage(&buf); pq_flush(); - /* - * Initialize position to the last ack'ed one, then the xlog records begin - * to be shipped from that position. - */ - logical_decoding_ctx = CreateDecodingContext(cmd->startpoint, cmd->options, - false, - logical_read_xlog_page, - WalSndPrepareWrite, - WalSndWriteData, - WalSndUpdateProgress); /* Start reading WAL from the oldest required WAL. */ logical_startptr = MyReplicationSlot->data.restart_lsn;