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sql: speed up fts query, report slow queries

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Fedor Indutny 2021-04-26 15:01:22 -07:00 • committed by GitHub
parent 26b90ba44a
commit dd173216ed
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4 changed files with 87 additions and 17 deletions
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46
ts/sql/Server.ts
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@ -2467,18 +2467,31 @@ async function searchMessages(
{ limit }: { limit?: number } = {}
): Promise<Array<SearchResultMessageType>> {
const db = getInstance();
// sqlite queries with a join on a virtual table (like FTS5) are de-optimized
// and can't use indices for ordering results. Instead an in-memory index of
// the join rows is sorted on the fly. The sorting becomes substantially
// slower when there are large columns in the in-memory index (like
// `messages.json`) so we do a query without them and then fetch large columns
// separately without using `ORDER BY` and `LIMIT`.
const rows: Array<SearchResultMessageType> = db
.prepare<Query>(
`
SELECT
messages.json,
snippet(messages_fts, -1, '<<left>>', '<<right>>', '...', 10) as snippet
FROM messages_fts
INNER JOIN messages on messages_fts.rowid = messages.rowid
WHERE
messages_fts match $query
ORDER BY messages.received_at DESC, messages.sent_at DESC
LIMIT $limit;
FROM
(SELECT
messages.rowid
FROM messages_fts
INNER JOIN messages ON messages_fts.rowid = messages.rowid
WHERE
messages_fts MATCH $query
ORDER BY messages.received_at DESC, messages.sent_at DESC
LIMIT $limit) AS results
INNER JOIN messages ON messages.rowid = results.rowid
INNER JOIN messages_fts ON messages_fts.rowid = results.rowid
WHERE messages_fts MATCH $query;
`
)
.all({
@ -2495,19 +2508,28 @@ async function searchMessagesInConversation(
{ limit }: { limit?: number } = {}
): Promise<Array<SearchResultMessageType>> {
const db = getInstance();
// See `searchMessages` for the explanation of the query
const rows = db
.prepare<Query>(
`
SELECT
messages.json,
snippet(messages_fts, -1, '<<left>>', '<<right>>', '...', 10) as snippet
FROM messages_fts
INNER JOIN messages on messages_fts.rowid = messages.rowid
FROM
(SELECT
messages.rowid
FROM messages_fts
INNER JOIN messages ON messages_fts.rowid = messages.rowid
WHERE
messages_fts MATCH $query
ORDER BY messages.received_at DESC, messages.sent_at DESC
LIMIT $limit) AS results
INNER JOIN messages ON messages.rowid = results.rowid
INNER JOIN messages_fts ON messages_fts.rowid = results.rowid
WHERE
messages_fts match $query AND
messages.conversationId = $conversationId
ORDER BY messages.received_at DESC, messages.sent_at DESC
LIMIT $limit;
messages_fts MATCH $query AND
messages.conversationId = $conversationId;
`
)
.all({