-- ===================================================================================================================
-- Collector: BlockingCollector ("blocking")
-- ===================================================================================================================
-- Hvad:        Blokerede sessioner og deres blokerere lige nu, med sætning og åbne transaktioner.
-- Fil:         src/SQLInsight.Collectors/Concurrency/BlockingCollector.cs
-- Interval:    1 min som standard (SQLInsight:CollectorIntervals:blocking)
-- Versioner:   Alle (SQL Server 2000 og nyere)
--
-- Rettigheder til agentens login (se db/permissions/grant-least-privilege.sql; [agent] = agentens login):
--   GRANT VIEW SERVER STATE TO [agent];                -- SQL Server 2005-2019
--   GRANT VIEW SERVER PERFORMANCE STATE TO [agent];    -- SQL Server 2022+ (erstatter VIEW SERVER STATE)
--   GRANT VIEW SERVER SECURITY STATE TO [agent];       -- SQL Server 2022+
--   SQL Server 2000 har ikke VIEW SERVER STATE; se docs/legacy-versions.md (fx kræver DBCC SQLPERF(WAITSTATS) forhøjede rettigheder).
--
-- Bruges af:   SQLI-BLK-001
-- Read-only:   Ja: kun SELECT samt SET-sessionsindstillinger. Intet ændrer data, indstillinger eller objekter.
-- Kørsel:     Kør i SSMS som agentens login. Hver variant er sin egen batch (GO); en variant for en anden SQL Server-version
--             end din kan fejle - det er forventet. Agenten kører altid med sessionsindstillingerne i _collectors/InstanceProbe.sql.
-- ===================================================================================================================

-- Variant: SQL Server 2012 og nyere
-- Kilde: BlockingCollector.BuildSql2005(2012+)
-- Kode:  src/SQLInsight.Collectors/Concurrency/BlockingCollector.cs : BlockingCollector.BuildSql2005(version)
SELECT s.session_id, NULLIF(r.blocking_session_id, 0), COALESCE(r.status, s.status), r.wait_type, r.wait_time, r.wait_resource,
       DB_NAME(COALESCE(r.database_id, s.database_id)), s.login_name, s.host_name, s.program_name, s.open_transaction_count,
       LEFT(CASE WHEN r.sql_handle IS NOT NULL AND r.statement_start_offset IS NOT NULL
                 THEN SUBSTRING(t.text, r.statement_start_offset / 2 + 1,
                      (CASE WHEN r.statement_end_offset = -1 THEN DATALENGTH(t.text) ELSE r.statement_end_offset END
                       - r.statement_start_offset) / 2 + 1)
                 ELSE t.text END, 4000),
       s.last_request_end_time
FROM sys.dm_exec_sessions s
LEFT JOIN sys.dm_exec_requests r ON r.session_id = s.session_id
LEFT JOIN sys.dm_exec_connections c ON c.session_id = s.session_id
OUTER APPLY sys.dm_exec_sql_text(COALESCE(r.sql_handle, c.most_recent_sql_handle)) t
WHERE r.blocking_session_id > 0
   OR s.session_id IN (SELECT blocking_session_id FROM sys.dm_exec_requests WHERE blocking_session_id > 0)
GO

-- Variant: SQL Server 2005 – 2008 R2
-- Kilde: BlockingCollector.BuildSql2005(2005)
-- Kode:  src/SQLInsight.Collectors/Concurrency/BlockingCollector.cs : BlockingCollector.BuildSql2005(version)
SELECT s.session_id, NULLIF(r.blocking_session_id, 0), COALESCE(r.status, s.status), r.wait_type, r.wait_time, r.wait_resource,
       DB_NAME(r.database_id), s.login_name, s.host_name, s.program_name, (SELECT COUNT(*) FROM sys.dm_tran_session_transactions st WHERE st.session_id = s.session_id),
       LEFT(CASE WHEN r.sql_handle IS NOT NULL AND r.statement_start_offset IS NOT NULL
                 THEN SUBSTRING(t.text, r.statement_start_offset / 2 + 1,
                      (CASE WHEN r.statement_end_offset = -1 THEN DATALENGTH(t.text) ELSE r.statement_end_offset END
                       - r.statement_start_offset) / 2 + 1)
                 ELSE t.text END, 4000),
       s.last_request_end_time
FROM sys.dm_exec_sessions s
LEFT JOIN sys.dm_exec_requests r ON r.session_id = s.session_id
LEFT JOIN sys.dm_exec_connections c ON c.session_id = s.session_id
OUTER APPLY sys.dm_exec_sql_text(COALESCE(r.sql_handle, c.most_recent_sql_handle)) t
WHERE r.blocking_session_id > 0
   OR s.session_id IN (SELECT blocking_session_id FROM sys.dm_exec_requests WHERE blocking_session_id > 0)
GO

-- Variant: SQL Server 2000 (legacy ODBC-sti)
-- Kilde: BlockingCollector.Sql2000
-- Kode:  src/SQLInsight.Collectors/Concurrency/BlockingCollector.cs : BlockingCollector.Sql2000
SELECT p.spid, NULLIF(CASE WHEN p.blocked = p.spid THEN 0 ELSE p.blocked END, 0), RTRIM(p.status), RTRIM(p.lastwaittype),
       p.waittime, RTRIM(p.waitresource), DB_NAME(p.dbid), RTRIM(p.loginame), RTRIM(p.hostname), RTRIM(p.program_name),
       p.open_tran, CAST(NULL AS nvarchar(4000)), p.last_batch
FROM master.dbo.sysprocesses p
WHERE (p.blocked > 0 AND p.blocked <> p.spid)
   OR p.spid IN (SELECT blocked FROM master.dbo.sysprocesses WHERE blocked > 0 AND blocked <> spid)
GO