feat(eap-items): add version column to eap_items_1_downsample_512_local

[onewland]

Stack

1. feat(eap-items): add version column to eap_items_1 #8424 — eap_items_1 (merged)
2. feat(eap-items): add version column to eap_items_1_downsample_8_local #8428 — eap_items_1_downsample_8_local
3. feat(eap-items): add version column to eap_items_1_downsample_64_local #8426 — eap_items_1_downsample_64_local
4. feat(eap-items): add version column to eap_items_1_downsample_512_local #8427 — eap_items_1_downsample_512_local
5. feat(eap-items): carry version through the downsample materialized views #8430 — downsample MVs carry version

Merge in order; each targets the one above it.

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Adds the version column to the downsample_512 tier.

ALTER TABLE eap_items_1_downsample_512_local ADD COLUMN IF NOT EXISTS version UInt64 DEFAULT 0 CODEC (ZSTD(1));

Why

Part of getting the eap_items schemas aligned with the target ReplacingMergeTree (keyed on version) so that existing parts can be attached onto the new tables. This mirrors the column added to eap_items_1 in migration 0064.

Schema-only — no engine change, so no dedup behaviour changes yet.

Why DEFAULT 0

ADD COLUMN does not rewrite existing parts, so rows written before this migration have no version on disk and the default is evaluated at read/merge time. That makes a non-deterministic default actively dangerous here: under ReplacingMergeTree(version) a now64() default gives legacy rows a version of "whenever the merge ran", which always beats a genuine write. Verified on CH 25.3 — a real update was silently discarded in favour of the stale row against a DEFAULT now64() destination, and won as expected against a DEFAULT 0 one.

0 is the sentinel for "written before versioning existed" and deterministically loses to every real write, matching the received_at precedent in snuba/manual_jobs/create_eap_received_at_version_test.py.

Why local only

Unlike 0064, this does not touch eap_items_1_downsample_512_dist (or _dist_ro):

• We never query version — it is internal bookkeeping for the cutover and is absent from the storage YAML, so the query layer cannot generate SQL naming it.
• The downsample tiers are fed by materialized views that write straight to *_local (swap_downsample_materialized_views uses destination_table_name={prefix}_local, target=OperationTarget.LOCAL), so the distributed table is never an insert target.

A Distributed table declaring a subset of its local table's columns behaves normally — verified that reads and SELECT * through the narrower dist table work, and that an insert routed through it still lets the local default fire. Only an explicit SELECT version through the dist table errors, and nothing does that.

Follow-up

The downsample MVs do not yet carry version through from the source, so rows they insert will read 0 rather than the source row's version. Fixing that needs an MV rebuild and is deliberately out of scope here.

Testing

• tests/migrations/test_runner.py::test_no_schema_differences
• tests/migrations/test_runner.py::test_run_and_reverse_all

[github-actions]

This PR has a migration; here is the generated SQL for ./snuba/migrations/groups.py ()

-- start migrations

-- forward migration events_analytics_platform : 0065_add_version_column_downsample_8
Local op: ALTER TABLE eap_items_1_downsample_8_local ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS version UInt64 DEFAULT 0 CODEC (ZSTD(1));
-- end forward migration events_analytics_platform : 0065_add_version_column_downsample_8




-- backward migration events_analytics_platform : 0065_add_version_column_downsample_8
Local op: ALTER TABLE eap_items_1_downsample_8_local ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS version;
-- end backward migration events_analytics_platform : 0065_add_version_column_downsample_8
-- forward migration events_analytics_platform : 0066_add_version_column_downsample_64
Local op: ALTER TABLE eap_items_1_downsample_64_local ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS version UInt64 DEFAULT 0 CODEC (ZSTD(1));
-- end forward migration events_analytics_platform : 0066_add_version_column_downsample_64




-- backward migration events_analytics_platform : 0066_add_version_column_downsample_64
Local op: ALTER TABLE eap_items_1_downsample_64_local ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS version;
-- end backward migration events_analytics_platform : 0066_add_version_column_downsample_64
-- forward migration events_analytics_platform : 0067_add_version_column_downsample_512
Local op: ALTER TABLE eap_items_1_downsample_512_local ON CLUSTER 'cluster_one_sh' ADD COLUMN IF NOT EXISTS version UInt64 DEFAULT 0 CODEC (ZSTD(1));
-- end forward migration events_analytics_platform : 0067_add_version_column_downsample_512




-- backward migration events_analytics_platform : 0067_add_version_column_downsample_512
Local op: ALTER TABLE eap_items_1_downsample_512_local ON CLUSTER 'cluster_one_sh' DROP COLUMN IF EXISTS version;
-- end backward migration events_analytics_platform : 0067_add_version_column_downsample_512