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|ID||Project||Category||View Status||Date Submitted||Last Update|
|0003288||Composr||core_database_drivers||public||2017-05-16 22:47||2019-11-26 22:11|
|Reporter||Chris Graham||Assigned To|
|Fixed in Version|
|Summary||0003288: Major overhaul of fulltext search support|
|Description||We can implement support for fulltext search on all database drivers, regardless of whether the database backends support it.|
This is doable via an 'inverted index'. Essentially we just do our own word tokenisation and store it in our own table.
An advantage to this is we can then do much more sophisticated metrics to stop slow searches. We could have fields in our inverted index table for all search qualifiers (post time, author, etc), so that we know we can easily only ever be looking at a subset of the index. Currently the problem with MySQL fulltext search is that the index can not be done against search qualifiers, so you get this huge trawl through non-qualified results as it gets to the occasional qualified ones.
If we do this, I see no reason we can't just drop the regular fulltext search support we have. We can do better, so there's no need to do anything native to each database backend.
This depends on 0003958 - we don't want to be populating the index when the server is under high load.
|Additional Information||Alternatively we can also implement more fulltext search support for individual databases.|
DB2, Oracle, and Sqlite (with non-default extension), also support fulltext search but we don't implement it.
If we do this we will need to totally overhaul our fulltext search code too because our code currently assumes it works via indexes, which is not a universally valid assumption. Particularly when indexes are deleted, it doesn't even go into the database driver API for that.
I prefer to implement our own fulltext rather than make a complex multi-vendor API, with lots of testing. It'd be a better result for less investment.
|Tags||ocProducts client-work (likely), Type: Performance|
|Time estimation (hours)||32|
||I think each existing full text index would need to be replaced with its own new table - we couldn't just use one table. And each table would need to have additional properties beyond ID & word, to allow multi-dimensional indexing. Otherwise we're not going to get the speed boosts we need. For example, for the forum posts search it would need to have forum IDs in there, so that it can have word & forum ID in a single index and easily carve out the result sets needed.|
1) multi-dimensional indexing. Full text gets very slow because it hits the full text index for a set of matching post IDs but then it has to intersect these against other search parameters, such as forum ID. For a popular term such as 'comcode' this may mean MySQL skipping through 100s of posts that match the term for every 1 it finds in the right forum. With our own custom multi-dimensional index we have those intersections precomputed.
2) background indexing. We can populate the indexing in the background, rather than real-time. Meaning we can have our expansive indexing with no performance hit.
3) custom stop word lists and min-max word lengths. MySQL's list of stop words ('the', 'an', etc) is compiled in, as is the word lengths. With our own implementation we would have much more control. I'm sure there's words not included in searches that we want, and words so common that their presence in queries really bogs down index traversal.
4) searches no longer creating read locks. As searching right now has to do the aforementioned intersecting against post data held in the main f_posts table, it will create read locks (which block writes). We could massively reduce read locking if the main work is happening in isolated indexes rather than the main table.
|2017-05-16 22:47||Chris Graham||New Issue|
|2017-05-16 22:47||Chris Graham||Tag Attached: Type: Performance|
|2017-05-16 23:16||Chris Graham||Additional Information Updated||View Revisions|
|2017-06-23 02:41||Chris Graham||Relationship added||related to 0001479|
|2017-07-05 13:13||Chris Graham||Tag Attached: ocProducts client-work (likely)|
|2018-02-07 20:29||Chris Graham||Tag Detached: ocProducts client-work (likely)|
|2019-07-19 01:45||Chris Graham||Relationship added||related to 0003848|
|2019-07-31 19:25||Chris Graham||Relationship added||related to 0001573|
|2019-11-14 22:02||Chris Graham||Tag Attached: Roadmap: v12|
|2019-11-14 22:02||Chris Graham||Tag Attached: ocProducts client-work (likely)|
|2019-11-18 02:36||Chris Graham||Note Added: 0006156|
|2019-11-18 02:45||Chris Graham||Note Added: 0006157|
|2019-11-18 02:45||Chris Graham||Note Edited: 0006157||View Revisions|
|2019-11-19 01:17||Chris Graham||Relationship added||related to 0003958|
|2019-11-19 01:17||Chris Graham||Description Updated||View Revisions|
|2019-11-26 22:11||Chris Graham||Tag Detached: Roadmap: v12|