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[[index-modules-translog]]
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== Translog
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Each shard has a transaction log or write ahead log associated with it.
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It allows to guarantee that when an index/delete operation occurs, it is
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applied atomically, while not "committing" the internal Lucene index for
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each request. A flush ("commit") still happens based on several
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parameters:
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2014-07-31 08:06:06 -04:00
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`index.translog.flush_threshold_ops`::
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2014-07-31 08:06:06 -04:00
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After how many operations to flush. Defaults to `unlimited`.
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2014-07-31 08:06:06 -04:00
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`index.translog.flush_threshold_size`::
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2014-07-31 08:06:06 -04:00
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Once the translog hits this size, a flush will happen. Defaults to `200mb`.
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`index.translog.flush_threshold_period`::
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The period with no flush happening to force a flush. Defaults to `30m`.
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`index.translog.interval`::
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How often to check if a flush is needed, randomized
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between the interval value and 2x the interval value. Defaults to `5s`.
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`index.gateway.local.sync`::
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How often the translog is ++fsync++ed to disk. Defaults to `5s`.
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2013-08-28 19:24:34 -04:00
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Note: these parameters can be updated at runtime using the Index
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Settings Update API (for example, these number can be increased when
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executing bulk updates to support higher TPS)
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