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Diffstat (limited to 'iredis/data/commands/xdel.md')
| -rw-r--r-- | iredis/data/commands/xdel.md | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/iredis/data/commands/xdel.md b/iredis/data/commands/xdel.md index 3f507a8..3ee4a3d 100644 --- a/iredis/data/commands/xdel.md +++ b/iredis/data/commands/xdel.md @@ -1,30 +1,30 @@ Removes the specified entries from a stream, and returns the number of entries -deleted, that may be different from the number of IDs passed to the command in -case certain IDs do not exist. +deleted. This number may be less than the number of IDs passed to the command in +the case where some of the specified IDs do not exist in the stream. Normally you may think at a Redis stream as an append-only data structure, -however Redis streams are represented in memory, so we are able to also delete -entries. This may be useful, for instance, in order to comply with certain -privacy policies. +however Redis streams are represented in memory, so we are also able to +delete entries. This may be useful, for instance, in order to comply with +certain privacy policies. -# Understanding the low level details of entries deletion +## Understanding the low level details of entries deletion -Redis streams are represented in a way that makes them memory efficient: a radix -tree is used in order to index macro-nodes that pack linearly tens of stream -entries. Normally what happens when you delete an entry from a stream is that -the entry is not _really_ evicted, it just gets marked as deleted. +Redis streams are represented in a way that makes them memory efficient: +a radix tree is used in order to index macro-nodes that pack linearly tens +of stream entries. Normally what happens when you delete an entry from a stream +is that the entry is not *really* evicted, it just gets marked as deleted. Eventually if all the entries in a macro-node are marked as deleted, the whole -node is destroyed and the memory reclaimed. This means that if you delete a -large amount of entries from a stream, for instance more than 50% of the entries -appended to the stream, the memory usage per entry may increment, since what -happens is that the stream will start to be fragmented. However the stream -performances will remain the same. +node is destroyed and the memory reclaimed. This means that if you delete +a large amount of entries from a stream, for instance more than 50% of the +entries appended to the stream, the memory usage per entry may increment, since +what happens is that the stream will become fragmented. However the stream +performance will remain the same. In future versions of Redis it is possible that we'll trigger a node garbage -collection in case a given macro-node reaches a given amount of deleted entries. -Currently with the usage we anticipate for this data structure, it is not a good -idea to add such complexity. +collection in case a given macro-node reaches a given amount of deleted +entries. Currently with the usage we anticipate for this data structure, it is +not a good idea to add such complexity. @return |