Database Reference
In-Depth Information
Here are some statements you should be aware of:
ANALYZE TABLE
is used to check that table keys are correct.
ANALYZE
TABLE
returns status information, as seen here:
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▼
Input
ANALYZE TABLE orders;
▼
Output
+--------------------+---------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------------+---------+----------+----------+
| crashcourse.orders | analyze | status | OK |
+--------------------+---------+----------+----------+
CHECK TABLE
is used to check tables for a variety of problems. Indexes
are also checked on an ARIA or MyISAM table.
CHECK TABLE
sup-
ports a series of modes for use with ARIA or MyISAM tables.
CHANGED
checks tables that have changed since the last check,
EXTENDED
performs
the most thorough check,
FAST
only checks tables that were not closed
properly,
MEDIUM
checks all deleted links and performs key verification,
and
QUICK
perform a quick scan only. As seen here,
CHECK TABLE
found
and repaired a problem:
■
▼
Input
CHECK TABLE orders, orderitems;
▼
Output
+------------------------+-------+----------+----------------------------+
| Table | Op | Msg_type | Msg_text |
+------------------------+-------+----------+----------------------------+
| crashcourse.orders | check | status | OK |
| crashcourse.orderitems | check | warning | Table is marked as crashed |
| crashcourse.orderitems | check | status | OK |
+------------------------+-------+----------+----------------------------+
If ARIA or MyISAM table access produces incorrect and inconsistent
results, you might need to repair the table using
REPAIR TABLE
. This
statement should not be used frequently, and if regular use is required,
there is likely a far bigger problem that needs addressing.
■
If you delete large amounts of data from a table,
OPTIMIZE TABLE
should be used to reclaim previously used space, thus optimizing the
performance of the table.
■
