pgsql: Reduce lock levels of some ALTER TABLE cmds

Reduce lock levels of some ALTER TABLE cmds

VALIDATE CONSTRAINT

CLUSTER ON
SET WITHOUT CLUSTER

ALTER COLUMN SET STATISTICS
ALTER COLUMN SET ()
ALTER COLUMN RESET ()

All other sub-commands use AccessExclusiveLock

Simon Riggs and Noah Misch

Reviews by Robert Haas and Andres Freund

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/e5550d5fec66aa74caad1f79b79826ec64898688

Modified Files
--------------
doc/src/sgml/mvcc.sgml | 9 +-
doc/src/sgml/ref/alter_table.sgml | 38 ++++++-
src/backend/catalog/toasting.c | 51 ++++++---
src/backend/commands/cluster.c | 14 +--
src/backend/commands/createas.c | 4 +-
src/backend/commands/tablecmds.c | 174 ++++++++++++++++++-----------
src/backend/tcop/utility.c | 4 +-
src/backend/utils/adt/ruleutils.c | 33 +++++-
src/backend/utils/cache/relcache.c | 74 ++++++++++--
src/include/catalog/toasting.h | 8 +-
src/test/isolation/isolation_schedule | 1 +
src/test/regress/expected/alter_table.out | 81 ++++++++++++--
src/test/regress/sql/alter_table.sql | 29 +++++
13 files changed, 401 insertions(+), 119 deletions(-)