pgsql: Lag tracking for logical replication

Lag tracking for logical replication

Lag tracking is called for each commit, but we introduce
a pacing delay to ensure we don't swamp the lag tracker.

Author: Petr Jelinek, with minor pacing delay code from me

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/024711bb544645c8b1061e9f02b261e2e336981d

Modified Files
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src/backend/replication/logical/logical.c | 34 ++++++++++++++-----
src/backend/replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/pgoutput/pgoutput.c | 2 ++
src/backend/replication/slotfuncs.c | 3 +-
src/backend/replication/walsender.c | 45 ++++++++++++++++++++------
src/include/replication/logical.h | 15 ++++++---
src/include/replication/output_plugin.h | 1 +
7 files changed, 79 insertions(+), 23 deletions(-)