-- arch-review 2026-08-19 P5-3 (register row-35 class): the Notifications list
-- page's sort key gets its own index.
--
-- NotificationOutboxRepository.QueryAsync orders (CreatedAt DESC, NotificationId
-- DESC) (NotificationId breaks CreatedAt ties for deterministic OFFSET paging).
-- None of the existing Notifications indexes lead unconditionally on CreatedAt:
--   - IX_Notifications_Status_NextAttemptAt requires an equality on Status first.
--   - IX_Notifications_SourceSiteId_CreatedAt requires an equality on SourceSiteId first.
--   - IX_Notifications_Delivered is filtered to Status = 'Delivered' only.
-- So an unfiltered (or lightly filtered) page fell back to a full clustered-index
-- scan + sort. IX_Notifications_Created_NotificationId (CreatedAt DESC,
-- NotificationId DESC) makes a forward scan of the index deliver rows in the
-- requested order directly, so a page reads a Top-N off the index instead of
-- sorting the whole table on every COUNT + page request.
--
-- Notifications is small enough today that a plain (offline) index build is
-- fine. On an Enterprise edition instance where the table has grown large and
-- the Central UI must stay responsive, add WITH (ONLINE = ON) to the CREATE
-- INDEX below.
--
-- Run with QUOTED_IDENTIFIER ON. Several tables in this database carry filtered
-- indexes and persisted computed columns, and SQL Server refuses DDL/DML against
-- them with error 1934 when the session has QUOTED_IDENTIFIER OFF -- which is
-- exactly what `sqlcmd` gives you by default (pass -I, or keep this header). The
-- SETs sit in their own batch so they are in force when the statements after the
-- GO parse.
SET QUOTED_IDENTIFIER ON;
SET ANSI_NULLS ON;
GO

BEGIN TRANSACTION;
IF NOT EXISTS (
    SELECT * FROM [__EFMigrationsHistory]
    WHERE [MigrationId] = N'20260819201210_AddNotificationsListSortIndex'
)
BEGIN
    EXEC(N'CREATE INDEX [IX_Notifications_Created_NotificationId]
        ON [Notifications] ([CreatedAt] DESC, [NotificationId] DESC)');
END;

IF NOT EXISTS (
    SELECT * FROM [__EFMigrationsHistory]
    WHERE [MigrationId] = N'20260819201210_AddNotificationsListSortIndex'
)
BEGIN
    INSERT INTO [__EFMigrationsHistory] ([MigrationId], [ProductVersion])
    VALUES (N'20260819201210_AddNotificationsListSortIndex', N'10.0.7');
END;

COMMIT;
GO