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|Comment:||Mention the cell-overwrite optimization on the change log.|
|Timelines:||family | ancestors | descendants | both | trunk|
|Files:||files | file ages | folders|
|User & Date:||drh 2018-05-08 13:35:00|
|14:32||More details on the UPSERT documentation. check-in: 7ca811b29f user: drh tags: trunk|
|13:35||Mention the cell-overwrite optimization on the change log. check-in: d324d1a30e user: drh tags: trunk|
|16:43||Documentation for SQLITE_ENABLE_SORTER_REFERENCES. check-in: 183931a121 user: drh tags: trunk|
Changes to pages/changes.in.
36 36 <li> The [CLI] automatically intercepts the raw [EXPLAIN QUERY PLAN] 37 37 output an reformats it into an ASCII-art graph. 38 38 <li> Enhance the query planner to allow the [OR optimization] to proceed 39 39 even if the OR expression has also been converted into an IN 40 40 expression. Uses of the OR optimization are now also 41 41 [eqp-or-opt|more clearly shown] in the [EXPLAIN QUERY PLAN] output. 42 42 <p><b>Performance:</b> 43 +<li> [UPDATE] avoids writing database pages that do not actually change. 44 + For example, "UPDATE t1 SET x=25 WHERE y=?" becomes a no-op if the 45 + value in column x is already 25. Similarly, 46 + when doing [UPDATE] on records that span multiple pages, only write 47 + the subset of pages that contain the changed value(s). 43 48 <li> Queries that use ORDER BY and LIMIT now try to avoid computing 44 49 rows that cannot possibly come in under the LIMIT. This can greatly 45 50 improve performance of ORDER BY LIMIT queries, especially when the 46 51 LIMIT is small relative to the number of unrestricted output rows. 47 52 <li> Performance improvements in the LEMON-generated parser. 48 53 <p><b>Bug fixes:</b> 49 54 <li> For the right-hand table of a LEFT JOIN, compute the values