-- FlipAuditLogClusteredKey (2026-11-10, ScadaBridge#111, variant B2 of
-- docs/plans/2026-11-09-auditlog-clustered-key-benchmark.md). dbo.AuditLog clustered key
-- (EventId, OccurredAtUtc) -> (OccurredAtUtc, EventId) + aligned unique UX_AuditLog_EventId_Occurred
-- (EventId, OccurredAtUtc); the twelve non-clustered indexes are dropped first and rebuilt last,
-- unchanged and partition-aligned. Re-runnable (no-op on an already-flipped table).
--
-- OFFLINE whole-table rebuild: size the window from the real table first
--   SELECT SUM(used_page_count)*8/1024 AS MB FROM sys.dm_db_partition_stats WHERE object_id = OBJECT_ID('dbo.AuditLog');
-- (local reference: 631 MB / 300k rows rebuilt in ~9 s on an idle dev container; production I/O and
-- log growth differ — the whole table is rewritten in one transaction, so the log needs ~2x the
-- table size free). Take a backup first. Stop BOTH central nodes (old binaries' partition-switch
-- purge cannot switch a flipped table: their staging table hard-codes the old key — msg 4947,
-- rolled back, nothing purged). Rollback: FlipAuditLogClusteredKey.rollback.sql (same cost).
--
-- Run with QUOTED_IDENTIFIER ON (sqlcmd -I, or keep this header): AuditLog has persisted computed
-- columns and filtered indexes and SQL Server raises error 1934 otherwise.
SET QUOTED_IDENTIFIER ON;
SET ANSI_NULLS ON;
GO
BEGIN TRANSACTION;

IF 
(SELECT c.name FROM sys.index_columns ic
   JOIN sys.columns c ON c.object_id = ic.object_id AND c.column_id = ic.column_id
  WHERE ic.object_id = OBJECT_ID('dbo.AuditLog') AND ic.index_id = 1 AND ic.key_ordinal = 1) = N'EventId'
BEGIN

DECLARE @dropSql nvarchar(max) = N'';
SELECT @dropSql = @dropSql + N'DROP INDEX ' + QUOTENAME(i.name) + N' ON dbo.AuditLog;' + CHAR(10)
FROM sys.indexes i
WHERE i.object_id = OBJECT_ID('dbo.AuditLog') AND i.type = 2 AND i.name IN (
    N'IX_AuditLog_OccurredAtUtc', N'IX_AuditLog_Site_Occurred', N'IX_AuditLog_CorrelationId',
    N'IX_AuditLog_Channel_Status_Occurred', N'IX_AuditLog_Target_Occurred', N'IX_AuditLog_Execution',
    N'IX_AuditLog_ParentExecution', N'IX_AuditLog_Node_Occurred', N'IX_AuditLog_Kind_Occurred',
    N'IX_AuditLog_Actor_Occurred', N'IX_AuditLog_Unchained', N'IX_AuditLog_ChainSeq',
    N'UX_AuditLog_EventId_Occurred');
EXEC sp_executesql @dropSql;
    ALTER TABLE dbo.AuditLog DROP CONSTRAINT PK_AuditLog;
    ALTER TABLE dbo.AuditLog ADD CONSTRAINT PK_AuditLog PRIMARY KEY CLUSTERED (OccurredAtUtc, EventId)
        ON ps_AuditLog_Month(OccurredAtUtc);
    CREATE UNIQUE NONCLUSTERED INDEX UX_AuditLog_EventId_Occurred ON dbo.AuditLog (EventId, OccurredAtUtc)
        ON ps_AuditLog_Month(OccurredAtUtc);

CREATE NONCLUSTERED INDEX IX_AuditLog_OccurredAtUtc ON dbo.AuditLog (OccurredAtUtc DESC) INCLUDE (Status) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Site_Occurred ON dbo.AuditLog (SourceSiteId ASC, OccurredAtUtc DESC) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_CorrelationId ON dbo.AuditLog (CorrelationId) WHERE CorrelationId IS NOT NULL ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Channel_Status_Occurred ON dbo.AuditLog (Category ASC, Status ASC, OccurredAtUtc DESC) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Target_Occurred ON dbo.AuditLog (Target ASC, OccurredAtUtc DESC) WHERE Target IS NOT NULL ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Execution ON dbo.AuditLog (ExecutionId) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_ParentExecution ON dbo.AuditLog (ParentExecutionId) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Node_Occurred ON dbo.AuditLog (SourceNode, OccurredAtUtc) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Kind_Occurred ON dbo.AuditLog (Kind ASC, OccurredAtUtc DESC) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Actor_Occurred ON dbo.AuditLog (Actor ASC, OccurredAtUtc DESC) ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_Unchained ON dbo.AuditLog (OccurredAtUtc, EventId) WHERE ChainSeq IS NULL ON ps_AuditLog_Month(OccurredAtUtc);
CREATE NONCLUSTERED INDEX IX_AuditLog_ChainSeq ON dbo.AuditLog (ChainSeq) WHERE ChainSeq IS NOT NULL ON ps_AuditLog_Month(OccurredAtUtc);
END

INSERT INTO [__EFMigrationsHistory] ([MigrationId], [ProductVersion])
VALUES (N'20261110033732_FlipAuditLogClusteredKey', N'10.0.13');

COMMIT;
GO