Fixes cockroachdb#81008. We built the basic infrastructure to coalesce ranges across table boundaries back in 22.2 as part of cockroachdb#66063. We've enabled this optimization for secondary tenants since then, but hadn't for the system tenant because of two primary blockers: - cockroachdb#93617: SHOW RANGES was broken by coalesced ranges. - cockroachdb#84105: APIs to compute sizes for schema objects (used in our UI) was broken by coalesced ranges. In both these cases we baked in assumptions about there being a minimum of one-{table,index,partition}-per-range. These blockers didn't apply to secondary tenants at the time since they didn't have access to SHOW RANGES, nor the UI pages where these schema statistics were displayed. We've addressed both these blockers in the 23.1 cycle as part of bridging the compatibility between secondary tenants and yesteryear's system tenant. - cockroachdb#93644 revised SHOW RANGES and crdb_internal.ranges{,_no_leases}, both internally and its external UX, to accommodate ranges straddling table/database boundaries. - cockroachdb#96223 re-worked our SpanStats API to work in the face of coalesced ranges, addressing cockroachdb#84105. Release note (general change): CockroachDB would previously use separate ranges for each table, index, or partition. This is no longer true -- it's possible now to have multiple tables, indexes, and partitions to get packed into the same range. For users with many such "schema objects", this will reduce the total range count in their clusters. This is especially true if individual tables, indexes, or partitions are smaller than the default configured maximum range size (controlled using zone configs, specifically the range_max_bytes parameter). We made this change to improve scalability with respect to the number of schema objects, since the underlying range count now no longer a bottleneck. Users upgrading from 22.2, once finalizing their upgrade, may observe a round of range merges and snapshot transfers (to power said range merges) as a result of this change. If users want to opt-out of this optimization, they can use the following cluster setting: SET CLUSTER SETTING spanconfig.storage_coalesce_adjacent.enabled = false;

Commits

Commits on May 8, 2023

spanconfig: enable range coalescing by default