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Enable query classifier cache by default

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Enabling it will give a performance improvement and it offloads work from
the CPU. This leads to better and more complete utilization of system
resources.
This commit is contained in:
Markus Mäkelä
2018-08-22 08:52:28 +03:00
parent 13c04324cf
commit 1692765503
4 changed files with 64 additions and 17 deletions
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27
Documentation/Getting-Started/Configuration-Guide.md
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@ -552,26 +552,29 @@ _qc_sqlite_ - supports the following arguments:
#### `query_classifier_cache_size`
If present, enables and specifies the maximum size of the query classifier cache.
Specifies the maximum size of the query classifier cache. The default limit is
40% of total system memory.
If the query classifier cache has been enabled, MaxScale will, after a statement
has been parsed, store the classification result using the canonicalized version
of the statement as the key.
When the query classifier cache has been enabled, MaxScale will, after a
statement has been parsed, store the classification result using the
canonicalized version of the statement as the key.
When the classification result for a statement is needed, MaxScale will first
canonicalize the statement and check whether the result can be found in the cache.
If it can, the statement will not be parsed at all but the cached result is used.
If the classification result for a statement is needed, MaxScale will first
canonicalize the statement and check whether the result can be found in the
cache. If it can, the statement will not be parsed at all but the cached result
is used.
The configuration parameter takes one integer that specifies the maximum size of
the cache. The size of the cache can be specifed as explained [here](#sizes).
The configuration parameter takes one integer that specifies the maximum size
of the cache. The size of the cache can be specifed as explained [here](#sizes).
```
# 1MB query classifier cache
query_classifier_cache=1MB
query_classifier_cache_size=1MB
```
Note that MaxScale uses a separate cache for each worker thread. So, the total
amount of memory used at most by the cache is obtained by multiplying the
size specified here, with the number the worker threads used.
amount of memory used at most by the cache is obtained by multiplying the size
specified here, with the value of `threads`.
##### `log_unrecognized_statements`