Skip to content

Commit 678a860

Browse files
dimitri-furmandimitri-furman
committed
Added a tip on inefficient page compression (1540)
1 parent e261b94 commit 678a860

File tree

2 files changed

+297
-6
lines changed

2 files changed

+297
-6
lines changed

‎sqldb-tips/get-sqldb-tips-compat-level-100-only.sql‎

Lines changed: 148 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -188,7 +188,13 @@ DECLARE
188188
@FillFactorThreshold tinyint = 90,
189189

190190
-- 1510: The ratio of the remaining identity/sequence range to initial identity range (or maximum sequence range) that is considered too low
191-
@IdentitySequenceRangeExhaustionThresholdRatio decimal(3,2) = 0.2
191+
@IdentitySequenceRangeExhaustionThresholdRatio decimal(3,2) = 0.2,
192+
193+
-- 1540: The minimum number of total page compression attempts per partition of an index to consider it in this tip
194+
@PageCompressionAttemptsThreshold int = 100,
195+
196+
-- 1540: The ratio of successful page compression attempts to total page compression attempts that is considered too low
197+
@MinPageCompressionSuccessRatio decimal(3,2) = 0.5
192198
;
193199

194200
DECLARE @ExecStartTime datetimeoffset = SYSDATETIMEOFFSET();
@@ -287,7 +293,7 @@ VALUES
287293
(1, 1230, 'Data IOPS are close to workload group limit', 70, 'https://aka.ms/sqldbtipswiki#tip_id-1230', 'VIEW SERVER STATE'),
288294
(1, 1240, 'Workload group IO governance impact is significant', 40, 'https://aka.ms/sqldbtipswiki#tip_id-1240', 'VIEW SERVER STATE'),
289295
(1, 1250, 'Data IOPS are close to resource pool limit', 70, 'https://aka.ms/sqldbtipswiki#tip_id-1250', 'VIEW SERVER STATE'),
290-
(1, 1260, 'Resouce pool IO governance impact is significant', 40, 'https://aka.ms/sqldbtipswiki#tip_id-1260', 'VIEW SERVER STATE'),
296+
(1, 1260, 'Resource pool IO governance impact is significant', 40, 'https://aka.ms/sqldbtipswiki#tip_id-1260', 'VIEW SERVER STATE'),
291297
(1, 1270, 'Persistent Version Store size is large', 70, 'https://aka.ms/sqldbtipswiki#tip_id-1270', 'VIEW SERVER STATE'),
292298
(1, 1280, 'Paused resumable index operations found', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1280', 'VIEW DATABASE STATE'),
293299
(1, 1290, 'Clustered columnstore candidates found', 50, 'https://aka.ms/sqldbtipswiki#tip_id-1290', 'VIEW SERVER STATE'),
@@ -314,7 +320,8 @@ VALUES
314320
(1, 1500, 'Non-unique clustered indexes found', 65, 'https://aka.ms/sqldbtipswiki#tip_id-1500', 'VIEW DATABASE STATE'),
315321
(1, 1510, 'Most of the IDENTITY range is used', 95, 'https://aka.ms/sqldbtipswiki#tip_id-1510', 'VIEW DATABASE STATE'),
316322
(1, 1520, 'Most of the sequence range is used', 95, 'https://aka.ms/sqldbtipswiki#tip_id-1520', 'VIEW DATABASE STATE'),
317-
(1, 1530, 'Disabled or not trusted constraints found', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1530', 'VIEW DATABASE STATE')
323+
(1, 1530, 'Disabled or not trusted constraints found', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1530', 'VIEW DATABASE STATE'),
324+
(1, 1540, 'Page compression is ineffective for some indexes', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1540', 'VIEW SERVER STATE')
318325
;
319326

320327
-- Top queries
@@ -2644,6 +2651,144 @@ BEGIN CATCH
26442651
THROW;
26452652
END CATCH;
26462653

2654+
-- Page compression wasting CPU
2655+
IF EXISTS (SELECT 1 FROM @TipDefinition WHERE tip_id IN (1540) AND execute_indicator = 1)
2656+
2657+
BEGIN TRY
2658+
2659+
WITH
2660+
partition_size AS
2661+
(
2662+
SELECT p.object_id,
2663+
p.index_id,
2664+
p.partition_number,
2665+
p.data_compression_desc,
2666+
SUM(ps.used_page_count) * 8 / 1024. AS total_partition_size_mb,
2667+
SUM(ps.in_row_used_page_count) * 8 / 1024. AS in_row_partition_size_mb,
2668+
SUM(ps.row_overflow_used_page_count) * 8 / 1024. AS row_overflow_partition_size_mb,
2669+
SUM(ps.lob_used_page_count) * 8 / 1024. AS lob_partition_size_mb
2670+
FROM sys.partitions AS p
2671+
INNER JOIN sys.dm_db_partition_stats AS ps
2672+
ON p.partition_id = ps.partition_id
2673+
AND
2674+
p.object_id = ps.object_id
2675+
AND
2676+
p.index_id = ps.index_id
2677+
GROUP BY p.object_id,
2678+
p.index_id,
2679+
p.partition_number,
2680+
p.data_compression_desc
2681+
),
2682+
-- Look at index stats for each partition of an index
2683+
partition_stats AS
2684+
(
2685+
SELECT o.object_id,
2686+
i.name AS index_name,
2687+
i.type_desc AS index_type,
2688+
p.partition_number,
2689+
p.total_partition_size_mb,
2690+
p.in_row_partition_size_mb,
2691+
p.row_overflow_partition_size_mb,
2692+
p.lob_partition_size_mb,
2693+
SUM(p.total_partition_size_mb) OVER (PARTITION BY o.object_id) AS object_size_mb,
2694+
p.partition_number - ROW_NUMBER() OVER (
2695+
PARTITION BY o.object_id, i.name
2696+
ORDER BY p.partition_number
2697+
)
2698+
AS interval_group, -- used to pack contiguous partition intervals for the same object and index
2699+
ios.page_compression_attempt_count,
2700+
ios.page_compression_success_count
2701+
FROM sys.objects AS o
2702+
INNER JOIN sys.indexes AS i
2703+
ON o.object_id = i.object_id
2704+
INNER JOIN partition_size AS p
2705+
ON i.object_id = p.object_id
2706+
AND
2707+
i.index_id = p.index_id
2708+
CROSS APPLY sys.dm_db_index_operational_stats(DB_ID(), o.object_id, i.index_id, p.partition_number) AS ios -- assumption: a representative workload has populated index operational stats
2709+
WHERE i.type_desc IN ('CLUSTERED','NONCLUSTERED','HEAP')
2710+
AND
2711+
p.data_compression_desc = 'PAGE'
2712+
AND
2713+
o.is_ms_shipped = 0
2714+
AND
2715+
i.is_hypothetical = 0
2716+
AND
2717+
i.is_disabled = 0
2718+
AND
2719+
DATABASEPROPERTYEX(DB_NAME(), 'Updateability') = 'READ_WRITE' -- only produce this on primary
2720+
AND
2721+
ios.page_compression_attempt_count > @PageCompressionAttemptsThreshold
2722+
AND
2723+
ios.page_compression_success_count * 1.0 < @MinPageCompressionSuccessRatio * ios.page_compression_attempt_count
2724+
),
2725+
packed_partition_group AS
2726+
(
2727+
SELECT QUOTENAME(OBJECT_SCHEMA_NAME(object_id)) COLLATE DATABASE_DEFAULT AS schema_name,
2728+
QUOTENAME(OBJECT_NAME(object_id)) COLLATE DATABASE_DEFAULT AS object_name,
2729+
QUOTENAME(index_name) COLLATE DATABASE_DEFAULT AS index_name,
2730+
index_type COLLATE DATABASE_DEFAULT AS index_type,
2731+
SUM(total_partition_size_mb) AS partition_range_total_size_mb,
2732+
SUM(in_row_partition_size_mb) AS partition_range_in_row_size_mb,
2733+
SUM(row_overflow_partition_size_mb) AS partition_range_row_overflow_size_mb,
2734+
SUM(lob_partition_size_mb) AS partition_range_lob_size_mb,
2735+
SUM(page_compression_attempt_count) AS page_compression_attempt_count,
2736+
SUM(page_compression_success_count) AS page_compression_success_count,
2737+
CONCAT(MIN(partition_number), '-', MAX(partition_number)) AS partition_range,
2738+
MIN(object_size_mb) AS object_size_mb
2739+
FROM partition_stats
2740+
GROUP BY object_id,
2741+
index_name,
2742+
index_type,
2743+
interval_group
2744+
HAVING COUNT(1) > 0
2745+
),
2746+
packed_partition_group_agg AS
2747+
(
2748+
SELECT STRING_AGG(
2749+
CAST(CONCAT(
2750+
'schema: ', schema_name,
2751+
', object: ', object_name,
2752+
', index: ' + index_name,
2753+
', index type: ', index_type,
2754+
', object size (MB): ', FORMAT(object_size_mb, 'N'),
2755+
', partition range: ', partition_range,
2756+
', partition range total size (MB): ', FORMAT(partition_range_total_size_mb, 'N'),
2757+
' (in-row: ', FORMAT(partition_range_in_row_size_mb, 'N'),
2758+
', row overflow: ', FORMAT(partition_range_row_overflow_size_mb, 'N'),
2759+
', LOB: ', FORMAT(partition_range_lob_size_mb, 'N'),
2760+
'), page compression total attempts: ', FORMAT(page_compression_attempt_count, '#,0'),
2761+
', page compression successful attempts: ', FORMAT(page_compression_success_count, '#,0')
2762+
) AS nvarchar(max)), @CRLF
2763+
)
2764+
AS details
2765+
FROM packed_partition_group
2766+
HAVING COUNT(1) > 0
2767+
)
2768+
INSERT INTO @DetectedTip (tip_id, details)
2769+
SELECT 1540 AS tip_id,
2770+
CONCAT(
2771+
@NbspCRLF,
2772+
'Since database engine startup at ', CONVERT(varchar(20), si.sqlserver_start_time, 120),
2773+
' UTC:',
2774+
@CRLF,
2775+
ppga.details,
2776+
@CRLF
2777+
) AS details
2778+
FROM packed_partition_group_agg AS ppga
2779+
CROSS JOIN sys.dm_os_sys_info AS si
2780+
WHERE ppga.details IS NOT NULL
2781+
;
2782+
2783+
END TRY
2784+
BEGIN CATCH
2785+
IF ERROR_NUMBER() = 1222
2786+
INSERT INTO @SkippedTip (tip_id)
2787+
VALUES (1540);
2788+
ELSE
2789+
THROW;
2790+
END CATCH;
2791+
26472792
-- Missing indexes
26482793
IF EXISTS (SELECT 1 FROM @TipDefinition WHERE tip_id IN (1210) AND execute_indicator = 1)
26492794

‎sqldb-tips/get-sqldb-tips.sql‎

Lines changed: 149 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -185,7 +185,13 @@ DECLARE
185185
@FillFactorThreshold tinyint = 90,
186186

187187
-- 1510: The ratio of the remaining identity/sequence range to initial identity range (or maximum sequence range) that is considered too low
188-
@IdentitySequenceRangeExhaustionThresholdRatio decimal(3,2) = 0.2
188+
@IdentitySequenceRangeExhaustionThresholdRatio decimal(3,2) = 0.2,
189+
190+
-- 1540: The minimum number of total page compression attempts per partition of an index to consider it in this tip
191+
@PageCompressionAttemptsThreshold int = 100,
192+
193+
-- 1540: The ratio of successful page compression attempts to total page compression attempts that is considered too low
194+
@MinPageCompressionSuccessRatio decimal(3,2) = 0.5
189195
;
190196

191197
DECLARE @ExecStartTime datetimeoffset = SYSDATETIMEOFFSET();
@@ -275,7 +281,7 @@ VALUES
275281
(1, 1230, 'Data IOPS are close to workload group limit', 70, 'https://aka.ms/sqldbtipswiki#tip_id-1230', 'VIEW SERVER STATE'),
276282
(1, 1240, 'Workload group IO governance impact is significant', 40, 'https://aka.ms/sqldbtipswiki#tip_id-1240', 'VIEW SERVER STATE'),
277283
(1, 1250, 'Data IOPS are close to resource pool limit', 70, 'https://aka.ms/sqldbtipswiki#tip_id-1250', 'VIEW SERVER STATE'),
278-
(1, 1260, 'Resouce pool IO governance impact is significant', 40, 'https://aka.ms/sqldbtipswiki#tip_id-1260', 'VIEW SERVER STATE'),
284+
(1, 1260, 'Resource pool IO governance impact is significant', 40, 'https://aka.ms/sqldbtipswiki#tip_id-1260', 'VIEW SERVER STATE'),
279285
(1, 1270, 'Persistent Version Store size is large', 70, 'https://aka.ms/sqldbtipswiki#tip_id-1270', 'VIEW SERVER STATE'),
280286
(1, 1280, 'Paused resumable index operations found', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1280', 'VIEW DATABASE STATE'),
281287
(1, 1290, 'Clustered columnstore candidates found', 50, 'https://aka.ms/sqldbtipswiki#tip_id-1290', 'VIEW SERVER STATE'),
@@ -302,7 +308,8 @@ VALUES
302308
(1, 1500, 'Non-unique clustered indexes found', 65, 'https://aka.ms/sqldbtipswiki#tip_id-1500', 'VIEW DATABASE STATE'),
303309
(1, 1510, 'Most of the IDENTITY range is used', 95, 'https://aka.ms/sqldbtipswiki#tip_id-1510', 'VIEW DATABASE STATE'),
304310
(1, 1520, 'Most of the sequence range is used', 95, 'https://aka.ms/sqldbtipswiki#tip_id-1520', 'VIEW DATABASE STATE'),
305-
(1, 1530, 'Disabled or not trusted constraints found', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1530', 'VIEW DATABASE STATE')
311+
(1, 1530, 'Disabled or not trusted constraints found', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1530', 'VIEW DATABASE STATE'),
312+
(1, 1540, 'Page compression is ineffective for some indexes', 90, 'https://aka.ms/sqldbtipswiki#tip_id-1540', 'VIEW SERVER STATE')
306313
;
307314

308315
-- Top queries
@@ -2640,6 +2647,145 @@ BEGIN CATCH
26402647
THROW;
26412648
END CATCH;
26422649

2650+
-- Page compression wasting CPU
2651+
IF EXISTS (SELECT 1 FROM @TipDefinition WHERE tip_id IN (1540) AND execute_indicator = 1)
2652+
2653+
BEGIN TRY
2654+
2655+
WITH
2656+
partition_size AS
2657+
(
2658+
SELECT p.object_id,
2659+
p.index_id,
2660+
p.partition_number,
2661+
p.data_compression_desc,
2662+
SUM(ps.used_page_count) * 8 / 1024. AS total_partition_size_mb,
2663+
SUM(ps.in_row_used_page_count) * 8 / 1024. AS in_row_partition_size_mb,
2664+
SUM(ps.row_overflow_used_page_count) * 8 / 1024. AS row_overflow_partition_size_mb,
2665+
SUM(ps.lob_used_page_count) * 8 / 1024. AS lob_partition_size_mb
2666+
FROM sys.partitions AS p
2667+
INNER JOIN sys.dm_db_partition_stats AS ps
2668+
ON p.partition_id = ps.partition_id
2669+
AND
2670+
p.object_id = ps.object_id
2671+
AND
2672+
p.index_id = ps.index_id
2673+
GROUP BY p.object_id,
2674+
p.index_id,
2675+
p.partition_number,
2676+
p.data_compression_desc
2677+
),
2678+
-- Look at index stats for each partition of an index
2679+
partition_stats AS
2680+
(
2681+
SELECT o.object_id,
2682+
i.name AS index_name,
2683+
i.type_desc AS index_type,
2684+
p.partition_number,
2685+
p.total_partition_size_mb,
2686+
p.in_row_partition_size_mb,
2687+
p.row_overflow_partition_size_mb,
2688+
p.lob_partition_size_mb,
2689+
SUM(p.total_partition_size_mb) OVER (PARTITION BY o.object_id) AS object_size_mb,
2690+
p.partition_number - ROW_NUMBER() OVER (
2691+
PARTITION BY o.object_id, i.name
2692+
ORDER BY p.partition_number
2693+
)
2694+
AS interval_group, -- used to pack contiguous partition intervals for the same object and index
2695+
ios.page_compression_attempt_count,
2696+
ios.page_compression_success_count
2697+
FROM sys.objects AS o
2698+
INNER JOIN sys.indexes AS i
2699+
ON o.object_id = i.object_id
2700+
INNER JOIN partition_size AS p
2701+
ON i.object_id = p.object_id
2702+
AND
2703+
i.index_id = p.index_id
2704+
CROSS APPLY sys.dm_db_index_operational_stats(DB_ID(), o.object_id, i.index_id, p.partition_number) AS ios -- assumption: a representative workload has populated index operational stats
2705+
WHERE i.type_desc IN ('CLUSTERED','NONCLUSTERED','HEAP')
2706+
AND
2707+
p.data_compression_desc = 'PAGE'
2708+
AND
2709+
o.is_ms_shipped = 0
2710+
AND
2711+
i.is_hypothetical = 0
2712+
AND
2713+
i.is_disabled = 0
2714+
AND
2715+
DATABASEPROPERTYEX(DB_NAME(), 'Updateability') = 'READ_WRITE' -- only produce this on primary
2716+
AND
2717+
ios.page_compression_attempt_count > @PageCompressionAttemptsThreshold
2718+
AND
2719+
ios.page_compression_success_count * 1.0 < @MinPageCompressionSuccessRatio * ios.page_compression_attempt_count
2720+
),
2721+
packed_partition_group AS
2722+
(
2723+
SELECT QUOTENAME(OBJECT_SCHEMA_NAME(object_id)) COLLATE DATABASE_DEFAULT AS schema_name,
2724+
QUOTENAME(OBJECT_NAME(object_id)) COLLATE DATABASE_DEFAULT AS object_name,
2725+
QUOTENAME(index_name) COLLATE DATABASE_DEFAULT AS index_name,
2726+
index_type COLLATE DATABASE_DEFAULT AS index_type,
2727+
SUM(total_partition_size_mb) AS partition_range_total_size_mb,
2728+
SUM(in_row_partition_size_mb) AS partition_range_in_row_size_mb,
2729+
SUM(row_overflow_partition_size_mb) AS partition_range_row_overflow_size_mb,
2730+
SUM(lob_partition_size_mb) AS partition_range_lob_size_mb,
2731+
SUM(page_compression_attempt_count) AS page_compression_attempt_count,
2732+
SUM(page_compression_success_count) AS page_compression_success_count,
2733+
CONCAT(MIN(partition_number), '-', MAX(partition_number)) AS partition_range,
2734+
MIN(object_size_mb) AS object_size_mb
2735+
FROM partition_stats
2736+
GROUP BY object_id,
2737+
index_name,
2738+
index_type,
2739+
interval_group
2740+
HAVING COUNT(1) > 0
2741+
),
2742+
packed_partition_group_agg AS
2743+
(
2744+
SELECT STRING_AGG(
2745+
CAST(CONCAT(
2746+
'schema: ', schema_name,
2747+
', object: ', object_name,
2748+
', index: ' + index_name,
2749+
', index type: ', index_type,
2750+
', object size (MB): ', FORMAT(object_size_mb, 'N'),
2751+
', partition range: ', partition_range,
2752+
', partition range total size (MB): ', FORMAT(partition_range_total_size_mb, 'N'),
2753+
' (in-row: ', FORMAT(partition_range_in_row_size_mb, 'N'),
2754+
', row overflow: ', FORMAT(partition_range_row_overflow_size_mb, 'N'),
2755+
', LOB: ', FORMAT(partition_range_lob_size_mb, 'N'),
2756+
'), page compression total attempts: ', FORMAT(page_compression_attempt_count, '#,0'),
2757+
', page compression successful attempts: ', FORMAT(page_compression_success_count, '#,0')
2758+
) AS nvarchar(max)), @CRLF
2759+
)
2760+
WITHIN GROUP (ORDER BY object_size_mb DESC, object_name, index_name, partition_range, partition_range_total_size_mb)
2761+
AS details
2762+
FROM packed_partition_group
2763+
HAVING COUNT(1) > 0
2764+
)
2765+
INSERT INTO @DetectedTip (tip_id, details)
2766+
SELECT 1540 AS tip_id,
2767+
CONCAT(
2768+
@NbspCRLF,
2769+
'Since database engine startup at ', CONVERT(varchar(20), si.sqlserver_start_time, 120),
2770+
' UTC:',
2771+
@CRLF,
2772+
ppga.details,
2773+
@CRLF
2774+
) AS details
2775+
FROM packed_partition_group_agg AS ppga
2776+
CROSS JOIN sys.dm_os_sys_info AS si
2777+
WHERE ppga.details IS NOT NULL
2778+
;
2779+
2780+
END TRY
2781+
BEGIN CATCH
2782+
IF ERROR_NUMBER() = 1222
2783+
INSERT INTO @SkippedTip (tip_id)
2784+
VALUES (1540);
2785+
ELSE
2786+
THROW;
2787+
END CATCH;
2788+
26432789
-- Missing indexes
26442790
IF EXISTS (SELECT 1 FROM @TipDefinition WHERE tip_id IN (1210) AND execute_indicator = 1)
26452791

0 commit comments

Comments
 (0)