Configuration parameters
Querying and searching in Redis Stack can be tuned through multiple configuration parameters. Some of these parameters can only be set at load-time, while other parameters can be set either at load-time or at run-time.
Set configuration parameters at module load-time
Setting configuration parameters at load-time is done by appending arguments after the --loadmodule
argument when starting a server from the command line, or after the loadmodule
directive in a Redis config file. For example:
In redis.conf:
loadmodule ./redisearch.so [OPT VAL]...
From the Redis CLI, using the MODULE LOAD command:
127.0.0.6379> MODULE LOAD redisearch.so [OPT VAL]...
From the command line:
$ redis-server --loadmodule ./redisearch.so [OPT VAL]...
Set configuration parameters at run-time (for supported parameters)
RediSearch exposes the FT.CONFIG
endpoint to allow for the setting and retrieval of configuration parameters at run-time.
To set the value of a configuration parameter at run-time (for supported parameters), simply run:
FT.CONFIG SET OPT1 VAL1
Similarly, you can retrieve current configuration parameter values using:
FT.CONFIG GET OPT1
FT.CONFIG GET *
Values set using FT.CONFIG SET
are not persisted after server restart.
RediSearch configuration parameters
The following table summarizes which configuration parameters can be set at module load-time and run-time:
Configuration Parameter | Load-time | Run-time |
---|---|---|
TIMEOUT | ✅ | ✅ |
ON_TIMEOUT | ✅ | ✅ |
SAFEMODE deprecated in v1.6 | ✅ | ✅ |
CONCURRENT_WRITE_MODE | ✅ | ✅ |
EXTLOAD | ✅ | ✅ |
MINPREFIX | ✅ | ✅ |
MINSTEMLEN | ✅ | ✅ |
MAXPREFIXEXPANSIONS | ✅ | ✅ |
MAXDOCTABLESIZE | ✅ | ✅ |
MAXSEARCHRESULTS | ✅ | ✅ |
MAXAGGREGATERESULTS | ✅ | ✅ |
FRISOINI | ✅ | ✅ |
CURSOR_MAX_IDLE | ✅ | ✅ |
PARTIAL_INDEXED_DOCS | ✅ | ✅ |
GC_SCANSIZE | ✅ | ⬜ |
GC_POLICY | ✅ | ✅ |
NOGC | ✅ | ✅ |
FORK_GC_RUN_INTERVAL | ✅ | ✅ |
FORK_GC_RETRY_INTERVAL | ✅ | ✅ |
FORK_GC_CLEAN_THRESHOLD | ✅ | ✅ |
UPGRADE_INDEX | ✅ | ✅ |
OSS_GLOBAL_PASSWORD | ✅ | ⬜ |
DEFAULT_DIALECT | ✅ | ✅ |
VSS_MAX_RESIZE | ✅ | ✅ |
TIMEOUT
The maximum amount of time in milliseconds that a search query is allowed to run. If this time is exceeded, Redis returns the top results accumulated so far, or an error depending on the policy set with ON_TIMEOUT
. The timeout can be disabled by setting it to 0.
TIMEOUT
refers to query time only.- Parsing the query is not counted towards
TIMEOUT
. - If
TIMEOUT
was not reached during the search, finalizing operations such as loading document content or reducers continue.
Default
500
Example
$ redis-server --loadmodule ./redisearch.so TIMEOUT 100
ON_TIMEOUT
The response policy for queries that exceed the TIMEOUT
setting can be one of the following:
- RETURN: this policy will return the top results accumulated by the query until it timed out.
- FAIL: will return an error when the query exceeds the timeout value.
Default
RETURN
Example
$ redis-server --loadmodule ./redisearch.so ON_TIMEOUT fail
SAFEMODE
If present in the argument list, RediSearch will turn off concurrency for query processing and work in a single thread.
This is useful if data consistency is extremely important, and avoids a situation where deletion of documents while querying them can cause momentarily inconsistent results. For example, documents that were valid during the invocation of the query are not returned because they were deleted during query processing.
Default
Off (not present)
Example
$ redis-server --loadmodule ./redisearch.so SAFEMODE
CONCURRENT_WRITE_MODE
If enabled, write queries will be performed concurrently, but only the tokenization part is executed concurrently. The actual write operation still requires holding the Redis Global Lock.
Default
Not set - "disabled"
Example
$ redis-server --loadmodule ./redisearch.so CONCURRENT_WRITE_MODE
- Added in v1.6
EXTLOAD
If present, RediSearch will try to load an extension dynamic library from its specified file path. See Extensions for details.
Default
None
Example
$ redis-server --loadmodule ./redisearch.so EXTLOAD ./ext/my_extension.so
MINPREFIX
The minimum number of characters allowed for prefix queries (e.g., hel*
). Setting it to 1 can hurt performance.
Default
2
Example
$ redis-server --loadmodule ./redisearch.so MINPREFIX 3
MINSTEMLEN
The minimum word length to stem. The default value is 4
. Setting it lower than 4
can reduce performance.
Default
4
Example
$ redis-server --loadmodule ./redisearch.so MINSTEMLEN 3
MAXPREFIXEXPANSIONS
The maximum number of expansions allowed for query prefixes. Setting it too high can cause performance issues. If MAXPREFIXEXPANSIONS is reached, the query will continue with the first acquired results. The configuration is applicable for all affix queries including prefix, suffix, and infix (contains) queries.
Default
200
Example
$ redis-server --loadmodule ./redisearch.so MAXPREFIXEXPANSIONS 1000
MAXDOCTABLESIZE
The maximum size of the internal hash table used for storing the documents. Note: this configuration option doesn't limit the number of documents that can be stored. It only affects the hash table internal array maximum size. Decreasing this property can decrease the memory overhead in cases where the index holds a small number of documents that are constantly updated.
Default
1000000
Example
$ redis-server --loadmodule ./redisearch.so MAXDOCTABLESIZE 3000000
MAXSEARCHRESULTS
The maximum number of results to be returned by the FT.SEARCH
command if LIMIT is used.
Setting value to -1
will remove the limit.
Default
1000000
Example
$ redis-server --loadmodule ./redisearch.so MAXSEARCHRESULTS 3000000
MAXAGGREGATERESULTS
The maximum number of results to be returned by the FT.AGGREGATE
command if LIMIT is used.
Setting value to -1
will remove the limit.
Default
unlimited
Example
$ redis-server --loadmodule ./redisearch.so MAXAGGREGATERESULTS 3000000
FRISOINI
If present, load the custom Chinese dictionary from the specified path. See Using custom dictionaries for more details.
Default
Not set
Example
$ redis-server --loadmodule ./redisearch.so FRISOINI /opt/dict/friso.ini
CURSOR_MAX_IDLE
The maximum idle time (in ms) that can be set to the cursor api.
Default
300000
Example
$ redis-server --loadmodule ./redisearch.so CURSOR_MAX_IDLE 500000
- Added in v1.6
PARTIAL_INDEXED_DOCS
Enable/disable the Redis command filter. The filter optimizes partial updates of hashes and may avoid re-indexing the hash if changed fields are not part of the schema.
Considerations
The Redis command filter will be executed upon each Redis command. Though the filter is
optimized, this will introduce a small increase in latency on all commands.
This configuration is best used with partially indexed documents where the non-indexed fields are updated frequently.
Default
0
Example
$ redis-server --loadmodule ./redisearch.so PARTIAL_INDEXED_DOCS 1
- Added in v2.0.0
GC_SCANSIZE
The bulk size of the internal GC used for cleaning up indexes.
Default
100
Example
$ redis-server --loadmodule ./redisearch.so GC_SCANSIZE 10
GC_POLICY
The garbage collection policy. Supported policies are:
- FORK: uses a forked thread for garbage collection (v1.4.1 and above). This is the default GC policy since version 1.6.1 and is ideal for general purpose workloads.
- LEGACY: Uses a synchronous, in-process fork. This is ideal for read-heavy and append-heavy workloads with very few updates/deletes. Deprecated in v2.6.0.
Default
FORK
Example
$ redis-server --loadmodule ./redisearch.so GC_POLICY FORK
- When the
GC_POLICY
isFORK
it can be combined with the options below.
NOGC
If set, Garbage Collection is disabled for all indexes. This is used mainly for debugging and testing and should not be set by users.
Default
Not set
Example
$ redis-server --loadmodule ./redisearch.so NOGC
FORK_GC_RUN_INTERVAL
Interval (in seconds) between two consecutive fork GC
runs.
Default
30
Example
$ redis-server --loadmodule ./redisearch.so GC_POLICY FORK FORK_GC_RUN_INTERVAL 60
- Can only be combined with
GC_POLICY FORK
FORK_GC_RETRY_INTERVAL
Interval (in seconds) in which RediSearch will retry to run fork GC
in case of a failure. Usually, a failure could happen when the Redis fork API does not allow for more than one fork to be created at the same time.
Default
5
Example
$ redis-server --loadmodule ./redisearch.so GC_POLICY FORK FORK_GC_RETRY_INTERVAL 10
- Can only be combined with
GC_POLICY FORK
- Added in v1.4.16
FORK_GC_CLEAN_THRESHOLD
The fork GC
will only start to clean when the number of not cleaned documents exceeds this threshold, otherwise it will skip this run. While the default value is 100, it's highly recommended to change it to a higher number.
Default
100
Example
$ redis-server --loadmodule ./redisearch.so GC_POLICY FORK FORK_GC_CLEAN_THRESHOLD 10000
- Can only be combined with
GC_POLICY FORK
- Added in v1.4.16
UPGRADE_INDEX
This configuration is a special configuration option introduced to upgrade indices from v1.x RediSearch versions, otherwise known as legacy indices. This configuration option needs to be given for each legacy index, followed by the index name and all valid options for the index description (also referred to as the ON
arguments for following hashes) as described on ft.create api.
Default
There is no default for index name, and the other arguments have the same defaults as with the FT.CREATE
API.
Example
$ redis-server --loadmodule ./redisearch.so UPGRADE_INDEX idx PREFIX 1 tt LANGUAGE french LANGUAGE_FIELD MyLang SCORE 0.5 SCORE_FIELD MyScore PAYLOAD_FIELD MyPayload UPGRADE_INDEX idx1
- If the RDB file does not contain a legacy index that's specified in the configuration, a warning message will be added to the log file, and loading will continue.
- If the RDB file contains a legacy index that wasn't specified in the configuration, loading will fail and the server won't start.
OSS_GLOBAL_PASSWORD
Global Redis Community Edition cluster password that will be used to connect to other shards.
Default
Not set
Example
$ redis-server --loadmodule ./redisearch.so OSS_GLOBAL_PASSWORD password
- Only relevant when Coordinator is used
- Added in v2.0.3
DEFAULT_DIALECT
The default
DIALECT
to be used by FT.CREATE
, FT.AGGREGATE
, FT.EXPLAIN
, FT.EXPLAINCLI
, and FT.SPELLCHECK
.
See Query dialects
for more information.
Default
1
Example
$ redis-server --loadmodule ./redisearch.so DEFAULT_DIALECT 2
VSS_MAX_RESIZE
The maximum memory resize for vector similarity indexes in bytes. This value will override default memory limits if you need to allow for a large BLOCK_SIZE
.
Default
0
Example
$ redis-server --loadmodule ./redisearch.so VSS_MAX_RESIZE 52428800 # 50MB
- Added in v2.4.8