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Some further fixes/cleanup/wordsmithing of the doc changes.

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Josh Kupershmidt 2015-05-19 20:10:25 -04:00
parent c375c2009d
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1 changed files with 21 additions and 18 deletions
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doc/pg_repack.rst
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@ -429,31 +429,34 @@ earlier versions which could result in data corruption.
Details Details
------- -------
Full table repack Full Table Repacks
^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^
To perform a full table repack, pg_repack will: To perform a full-table repack, pg_repack will:
* create a log table 1. create a log table to record changes made to the original table
* create a trigger on the old table to log all changes to the log table 2. add a trigger onto the original table, logging INSERTs, UPDATEs and DELETEs into our log table
* create a new table containing all data in the old table 3. create a new table containing all the rows in the old table
* create all indexes on the new table 4. build indexes on this new table
* apply all changes from the log table to the new table 5. apply all changes which have accrued in the log table to the new table
* when the log table is empty, swap the table in the system catalog 6. swap the tables, including indexes and toast tables, using the system catalogs
* drop the old table 7. drop the original table
pg_repack will only acquire ACCESS EXCLUSIVE locks when creating the trigger and when pg_repack will only hold an ACCESS EXCLUSIVE lock for a short period during
switching the table files, all other operations are lock-free on the source table. initial setup (steps 1 and 2 above) and during the final swap-and-drop phase
(steps 6 and 7). For the rest of its time, pg_repack only needs
to hold an ACCESS SHARE lock on the original table, meaning INSERTs, UPDATEs,
and DELETEs may proceed as usual.
Index only repack Index Only Repacks
^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^
To perform a index only repack, pg_repack will: To perform an index-only repack, pg_repack will:
* create a new index on the table using CONCURRENTLY 1. create new indexes on the table using CONCURRENTLY matching the definitions of the old indexes
* swap the index in the catalog 2. swap out the old for the new indexes in the catalogs
* drop the old index 3. drop the old indexes
Creating indexes concurrently comes with a few caveats, please see `the documentation`__ for details. Creating indexes concurrently comes with a few caveats, please see `the documentation`__ for details.