Database.Guide – Page 143

Redis ZREVRANGE Replacement

January 6, 2023 by Ian

Starting with Redis 6.2.0, the ZRANGE command added the REV, BYSCORE, BYLEX and LIMIT options. The addition of the first three means that the ZRANGE command can now do what the ZREVRANGE, ZRANGEBYSCORE, ZREVRANGEBYSCORE, ZRANGEBYLEX and ZREVRANGEBYLEX commands can do.

As a result, those commands are now deprecated (as of Redis 6.2.0).

Therefore, we should no longer use the ZREVRANGE command when we need to return a sorted set in descending order. Instead, we should use the ZRANGE command with the REV argument.

6 Ways to Clone a Table in PostgreSQL

January 5, 2023 by Ian

PostgreSQL provides us with several options when it comes to cloning a table. Below are six methods we can use to clone a table in Postgres. The method we use will depend on things like, whether or not we want to transfer the data, indexes, etc.

Redis BZPOPMAX Command Explained

January 4, 2023 by Ian

In Redis, the BZPOPMAX command is the blocking variant of the ZPOPMAX command.

The BZPOPMAX command works similar to ZPOPMAX when any of the sorted sets contain elements. That is, it pops a member with the highest score from the sorted set.

Redis BZPOPMIN Command Explained

January 4, 2023 by Ian

In Redis, the BZPOPMIN command is the blocking variant of the ZPOPMIN command.

The BZPOPMIN command works similar to ZPOPMIN when any of the sorted sets contain elements. That is, it pops a member with the lowest score from the sorted set.

Redis ZPOPMAX Command Explained

January 4, 2023January 3, 2023 by Ian

In Redis, the ZMPOPMAX command removes and returns (pops) members with the highest scores from the specified sorted set. By default it pops one member, but we can also specify how many members we want to pop.

Redis ZPOPMIN Command Explained

January 4, 2023January 3, 2023 by Ian

In Redis, the ZMPOPMIN command removes and returns (pops) members with the lowest scores from the specified sorted set. By default it pops one member, but we can also specify how many members we want to pop.

Redis BZMPOP Command Explained

January 2, 2023 by Ian

In Redis, the BZMPOP command is the blocking variant of the ZMPOP command.

The BZMPOP command works exactly like ZMPOP when any of the sorted sets contain elements. It also works exactly like ZMPOP when used inside a MULTI/EXEC block. That is, it pops one or more elements from the first non-empty sorted set in the provided list of keys.

However, if all of the specified sorted sets are empty, then BZMPOP will block the connection until another client adds members to one of the keys or until the specified timeout elapses. It’s possible to block the connection indefinitely by using a timeout of zero.

Redis ZMPOP Command Explained

January 1, 2023January 1, 2023 by Ian

In Redis, the ZMPOP command removes and returns one or more elements from the first non-empty sorted set in the provided list of keys.

The ZMPOP command was introduced in Redis 7.0.0.

Redis ZCARD Command Explained

December 31, 2022 by Ian

In Redis, the ZCARD command returns the cardinality (number of elements) of a sorted set.

Redis ZINTERSTORE Command Explained

December 30, 2022 by Ian

In Redis, the ZINTERSTORE command computes the intersection of the specified sorted sets and stores the result in the specified key. It works the same as the ZINTER command, except that it stores the result instead of returning it.

If the destination key already exists, it’s overwritten.