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diff --git a/iredis/data/commands/zrangebylex.md b/iredis/data/commands/zrangebylex.md index 55f3002..4eefffc 100644 --- a/iredis/data/commands/zrangebylex.md +++ b/iredis/data/commands/zrangebylex.md @@ -1,59 +1,51 @@ -When all the elements in a sorted set are inserted with the same score, in order -to force lexicographical ordering, this command returns all the elements in the -sorted set at `key` with a value between `min` and `max`. +When all the elements in a sorted set are inserted with the same score, in order to force lexicographical ordering, this command returns all the elements in the sorted set at `key` with a value between `min` and `max`. -If the elements in the sorted set have different scores, the returned elements -are unspecified. +If the elements in the sorted set have different scores, the returned elements are unspecified. -The elements are considered to be ordered from lower to higher strings as -compared byte-by-byte using the `memcmp()` C function. Longer strings are -considered greater than shorter strings if the common part is identical. - -As per Redis 6.2.0, this command is considered deprecated. Please prefer using -the `ZRANGE` command with the `BYLEX` argument in new code. +The elements are considered to be ordered from lower to higher strings as compared byte-by-byte using the `memcmp()` C function. Longer strings are considered greater than shorter strings if the common part is identical. The optional `LIMIT` argument can be used to only get a range of the matching elements (similar to _SELECT LIMIT offset, count_ in SQL). A negative `count` -returns all elements from the `offset`. Keep in mind that if `offset` is large, -the sorted set needs to be traversed for `offset` elements before getting to the -elements to return, which can add up to O(N) time complexity. +returns all elements from the `offset`. +Keep in mind that if `offset` is large, the sorted set needs to be traversed for +`offset` elements before getting to the elements to return, which can add up to +O(N) time complexity. ## How to specify intervals -Valid _start_ and _stop_ must start with `(` or `[`, in order to specify if the -range item is respectively exclusive or inclusive. The special values of `+` or -`-` for _start_ and _stop_ have the special meaning or positively infinite and -negatively infinite strings, so for instance the command **ZRANGEBYLEX -myzset - +** is guaranteed to return all the elements in the sorted set, if all -the elements have the same score. +Valid *start* and *stop* must start with `(` or `[`, in order to specify +if the range item is respectively exclusive or inclusive. +The special values of `+` or `-` for *start* and *stop* have the special +meaning or positively infinite and negatively infinite strings, so for +instance the command **ZRANGEBYLEX myzset - +** is guaranteed to return +all the elements in the sorted set, if all the elements have the same +score. ## Details on strings comparison -Strings are compared as binary array of bytes. Because of how the ASCII -character set is specified, this means that usually this also have the effect of -comparing normal ASCII characters in an obvious dictionary way. However this is -not true if non plain ASCII strings are used (for example utf8 strings). +Strings are compared as binary array of bytes. Because of how the ASCII character +set is specified, this means that usually this also have the effect of comparing +normal ASCII characters in an obvious dictionary way. However this is not true +if non plain ASCII strings are used (for example utf8 strings). -However the user can apply a transformation to the encoded string so that the -first part of the element inserted in the sorted set will compare as the user -requires for the specific application. For example if I want to add strings that -will be compared in a case-insensitive way, but I still want to retrieve the -real case when querying, I can add strings in the following way: +However the user can apply a transformation to the encoded string so that +the first part of the element inserted in the sorted set will compare as the +user requires for the specific application. For example if I want to +add strings that will be compared in a case-insensitive way, but I still +want to retrieve the real case when querying, I can add strings in the +following way: ZADD autocomplete 0 foo:Foo 0 bar:BAR 0 zap:zap -Because of the first _normalized_ part in every element (before the colon -character), we are forcing a given comparison, however after the range is -queries using `ZRANGEBYLEX` the application can display to the user the second -part of the string, after the colon. +Because of the first *normalized* part in every element (before the colon character), we are forcing a given comparison, however after the range is queries using `ZRANGEBYLEX` the application can display to the user the second part of the string, after the colon. The binary nature of the comparison allows to use sorted sets as a general -purpose index, for example the first part of the element can be a 64 bit big -endian number: since big endian numbers have the most significant bytes in the -initial positions, the binary comparison will match the numerical comparison of -the numbers. This can be used in order to implement range queries on 64 bit -values. As in the example below, after the first 8 bytes we can store the value -of the element we are actually indexing. +purpose index, for example the first part of the element can be a 64 bit +big endian number: since big endian numbers have the most significant bytes +in the initial positions, the binary comparison will match the numerical +comparison of the numbers. This can be used in order to implement range +queries on 64 bit values. As in the example below, after the first 8 bytes +we can store the value of the element we are actually indexing. @return |