Read-only mode for connection disables any table or global modifications. So, queries like create, drop, all kinds of alter, attach, optimize, data modifications queries, such as insert, replace, delete, update and others will all be rejected. Changing daemon-wide settings via SET GLOBAL is also not possible in this mode.

You still can perform all search operations, generate snippets and run CALL PQ queries. Also, you can modify local (connection-wide) settings.

You can check, whether your current connection is read-only or not by executing show variables like 'session_read_only' statement. Value 1 means read-only, 0 - usual (not read-only).

Normally you define a separate listen directive in read-only mode by adding suffix _readonly to it, but you can also, do it interactively for the current connection by executing SET ro=1 statement via sql.

If you're connected to a vip socket, you can execute SET ro=0 (even if the socket you are connected to was defined read-only in config, not interactively), and the connection will switch to usual (not read-only) mode with all modifications allowed.

For usual (non-VIP) connections escaping read-only mode is only possible by reconnecting, if it was set read-only interactively, or updating the configuration file and restarting the daemon.

Query logging can be enabled by setting query_log directive in searchd section of the configuration file

searchd {
...
    query_log = /var/log/query.log
...
}

Queries can also be sent to syslog by setting syslog instead of a file path.

In this case all search queries will be sent to syslog daemon with LOG_INFO priority, prefixed with [query] instead of timestamp. Only plain log format is supported for syslog.

Two query log formats are supported:

• plain: recommended if most of your queries are purely full-text or you just don't care about non-full text components of your queries: filtering by attributes, sorting, grouping etc. You can't replay queries logged in plain format.
• sphinxql: recommended in all other cases (default). It also provides an easy way to replay logged queries.

With plain log format Manticore logs all successfully executed search queries into a query log file. Here's an example:

[Fri Jun 29 21:17:58 2007] 0.004 sec 0.004 sec [all/0/rel 35254 (0,20)] [lj] test
[Fri Jun 29 21:20:34 2007] 0.024 sec 0.024 sec [all/0/rel 19886 (0,20) @channel_id] [lj] test

The log format is as follows:

[query-date] real-time wall-time [match-mode/filters-count/sort-mode total-matches (offset,limit) @groupby-attr] [table-name] query

• real-time is the time from start till finish of the query
• wall-time is like the real-time, excluding time spent on waiting for agents and merging result sets from them

match-mode can have one of the following values:

• "all" for SPH_MATCH_ALL mode;
• "any" for SPH_MATCH_ANY mode;
• "phr" for SPH_MATCH_PHRASE mode;
• "bool" for SPH_MATCH_BOOLEAN mode;
• "ext" for SPH_MATCH_EXTENDED mode;
• "ext2" for SPH_MATCH_EXTENDED2 mode;
• "scan" if the full scan mode was used, either by being specified with SPH_MATCH_FULLSCAN or if the query was empty.

sort-mode can have one of the following values:

• "rel" for SPH_SORT_RELEVANCE mode;
• "attr-" for SPH_SORT_ATTR_DESC mode;
• "attr+" for SPH_SORT_ATTR_ASC mode;
• "tsegs" for SPH_SORT_TIME_SEGMENTS mode;
• "ext" for SPH_SORT_EXTENDED mode.

Note: the SPH* modes are specific to sphinx legacy interface. SQL and HTTP interfaces will log in most cases ext2 as match-mode and ext and rel as sort-mode.

If Manticore was started with --iostats (ot it was enabled via SET GLOBAL iostats=1) the corresponding metrics will be included in the log. Then a query log entry might take the form of:

[Fri Jun 29 21:17:58 2021] 0.004 sec [all/0/rel 35254 (0,20)] [lj] [ios=6 kb=111.1 ms=0.5] test

where:

• ios - number of file I/O operations carried out;
• kb - amount of data in kilobytes read from the table files;
• ioms - time spent on I/O operations.

If Manticore was started with --cpustats (ot it was enabled via SET GLOBAL cpustats=1) metric cpums will be included in the log. The query log will then look so:

[Fri Jun 29 21:17:58 2021] 0.004 sec [all/0/rel 35254 (0,20)] [lj] [ios=6 kb=111.1 ms=0.5 cpums=0.3] test

where cpums is time in milliseconds spent on CPU processing the query.

SQL format is default, but can be changed by searchd setting query_log_format:

searchd {
...
    query_log = /var/log/query.log
    query_log_format = sphinxql
...
}

In this format, the example from the previous section would look as follows. (Wrapped below for readability, but with just one query per line in the actual log.)

/* Fri Jun 29 21:17:58.609 2007 2011 conn 2 real 0.004 wall 0.004 found 35254 */
SELECT * FROM test WHERE MATCH('test') OPTION ranker=proximity;

/* Fri Jun 29 21:20:34 2007.555 conn 3 real 0.024 wall 0.024 found 19886 */
SELECT * FROM test WHERE MATCH('test') GROUP BY channel_id OPTION ranker=proximity;

Note that all requests would be logged in this format, including those sent via SphinxAPI and SphinxSE, not just those sent via SQL. Also note, that this kind of logging works only with plain log files and will not work if you use 'syslog' service for logging.

The features of Manticore SQL log format compared to the plain text one are as follows:

• Full statement data will be logged where possible.
• Errors and warnings are logged.
• Query log can be replayedL.
• Additional performance counters (currently, per-agent distributed query times) are logged.

Use sphinxql:compact_in to shorten your IN() clauses in log if you have too many values in it.

Every request (including both SphinxAPI and SQL) request results in exactly one log line. Every log line must be a valid Manticore SQL statement that reconstructs the full request, except if the logged request is too big and needs shortening for performance reasons. Additional messages, counters, etc. can be logged in the comments section after the request.

By default all queries are logged. If it's desired to log only queries with execution times that exceed the specified limit, the query_log_min_msec directive can be used:

searchd {
...
    query_log = /var/log/query.log
    query_log_min_msec  = 1000
...
}

The expected unit of measurerement is milliseconds, but time suffix expressions can be used as well, like:

searchd {
...
    query_log = /var/log/query.log
    query_log_min_msec  = 1s
...
}

By default the searchd and query log files are created with permission 600, so only the user under which Manticore is running and root can read the log files. query_log_mode allows setting a different permission. This can be handy to allow other users to be able to read the log files (for example monitoring solutions running on non-root users).

searchd {
...
    query_log = /var/log/query.log
    query_log_mode = 666
...
}