A reversed range
The higher bound comes first, which is what REV requires
- key
- leaderboard
- by
- score
- min
- 100
- max
- 500
- reverse
- yes
Redis ZRANGE Query Builder
Build a ZRANGE. The bug this exists to prevent: with REV, the higher bound comes first. Writing the arguments in the order you say them out loud returns an empty result with no error at all.
zrange-command.txt
updates as you typeExamples
Worked setups you can load into the form above. Each one is a decision the generator makes differently, and the reason it makes it.
LIMIT on an index range
A combination Redis rejects, because index ranges already take start and stop
- key
- leaderboard
- by
- index
- min
- 0
- max
- -1
- limit
- 0 10
Common mistakes
These are the ones that fail silently. The config is accepted, nothing raises an error, and the consequence arrives later.
Writing REV bounds low then high
REV expects the higher bound first. The other order describes an empty range and returns nothing, with no error.
Instead:Put the high bound first when using REV.
Paginating with an index range and LIMIT
LIMIT is not valid with an index range.
Instead:Use BYSCORE with LIMIT offset count.
Using BYLEX on a set with varying scores
Lexicographic order only holds when every member shares a score. Otherwise the result is not alphabetical.
Instead:Use a single score, conventionally 0, or use BYSCORE.
Dropping the parenthesis on an exclusive bound
Bounds are inclusive by default, so the range quietly includes one extra element.
Instead:Keep ( attached to the value.
One command, three range types, and an argument order that flips
Redis 6.2 merged six commands into ZRANGE. The options are clearer than the old names, and two of them interact in ways that fail silently.
REV swaps which bound comes first
Without REV you give the low bound then the high one. With REV you give the HIGH bound then the low one. Getting it the wrong way round is not an error: it describes an empty range, so Redis returns nothing and nothing explains why. This is the most common ZRANGE bug there is.
LIMIT only exists for BYSCORE and BYLEX
An index range already takes a start and a stop, so an offset and count would be meaningless and Redis rejects the combination. For score ranges LIMIT is how pagination works, and it is the reason to prefer BYSCORE over index ranges for paging.
BYLEX is only meaningful when every score is identical
Lexicographic ordering assumes the set is ordered by member. If scores differ, the ordering is by score first, and the result is not the alphabetical range it appears to be. Nothing warns about this, because it is a valid query over a set that happens to be shaped differently than assumed.
A leading parenthesis makes a bound exclusive
Bounds are inclusive by default and the parenthesis is the only way to exclude an endpoint. It is easy to lose when a bound is built by string concatenation, and losing it produces an off-by-one that is invisible in the query.
The old commands still work
ZRANGEBYSCORE, ZREVRANGE and the rest are soft-deprecated rather than removed. On a server older than 6.2 they are the only option, because ZRANGE there does not accept BYSCORE, BYLEX or REV.
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