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Overview
| Comment: | Fix a typo on the optoverview.html document. |
|---|---|
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: | 5272d8d61daf61ca00bac53a319ff3c1 |
| User & Date: | drh 2018-04-12 17:04:32 |
Context
|
2018-04-12
| ||
| 18:08 | Fix yet another typo in whynotgit.html check-in: 13eff8bb25 user: drh tags: trunk | |
| 17:04 | Fix a typo on the optoverview.html document. check-in: 5272d8d61d user: drh tags: trunk | |
| 15:31 | There are "hundreds of billions", not "tens of billions" of SQLite database files in circulation - in the rowidtable.html document. check-in: c34168d55b user: drh tags: trunk | |
Changes
Changes to pages/optoverview.in.
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table smaller, and helps the subquery to run faster if there
is an index on t1.b. The resulting evaluation is like this:
<codeblock>
SELECT x, y, b
FROM t2
JOIN (SELECT DISTINCT a, b FROM t1 WHERE b BETWEEN 10 AND 20)
WHERE b BETWEEN 10 AND 10;
</codeblock>
<p>
The push-down optimization cannot always be used. For example,
if the subquery contains a LIMIT, then pushing down any part of
the WHERE clause from the outer query could change the result of
the inner query. There are other restrictions, explained in a
|
| |
1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 |
table smaller, and helps the subquery to run faster if there
is an index on t1.b. The resulting evaluation is like this:
<codeblock>
SELECT x, y, b
FROM t2
JOIN (SELECT DISTINCT a, b FROM t1 WHERE b BETWEEN 10 AND 20)
WHERE b BETWEEN 10 AND 20;
</codeblock>
<p>
The push-down optimization cannot always be used. For example,
if the subquery contains a LIMIT, then pushing down any part of
the WHERE clause from the outer query could change the result of
the inner query. There are other restrictions, explained in a
|