Paul White
answers / questions / communities
answer date/timequestion typetitleanswer starsquestion date/time
2020-05-23 14:35QuestionWhy does adding a TOP allow the SQL Server query optimizer to find a plan that can honor a FORCESEEK hint?122020-05-22 22:49
2020-05-23 13:37QuestionMissed optimisations for ScalarGbAggToTop with MAX(nullable_column)122020-05-22 17:59
2020-05-11 11:07QuestionSQL Server Spill level 0 - what is it?52020-05-11 10:48
2020-04-22 13:32QuestionWhy doesn't disabling row goals give me a different query plan?142020-04-22 03:33
2020-04-16 10:00QuestionHow can this MAXDOP 4 query have CPU time greater than 4X the elapsed time?132020-04-16 04:43
2020-04-16 14:13QuestionEXCEPT & INTERSECT: Purpose of Passive Projection in Logical Plan72020-04-16 03:09
2020-04-07 14:51QuestionHow do you add line returns after every nth item in a string?62020-04-06 13:51
2020-03-30 11:27QuestionExecution plan depends on predicate comparison order82020-03-28 00:21
2020-03-10 14:23QuestionCursoring over sys.databases skips databases122020-03-09 17:06
2020-03-06 13:51QuestionWhat are the use-cases for ACCELERATED_PLAN_FORCING?132020-03-05 19:57
2020-03-02 13:42QuestionDisabling function inlining does not reflect on system catalog92020-03-02 12:47
2020-03-14 13:13QuestionWhy are (seemingly) suitable indexes not used on a LEFT JOIN with OR62020-02-28 23:48
2019-12-21 09:06QuestionALTER fixed-length COLUMN on compressed table82019-12-20 15:08
2019-12-16 12:52QuestionSometimes the updated rows are not locked within instead of update trigger22019-12-16 09:57
2019-12-05 22:53QuestionWhy/when does SQL Server evaluate the probe side of an inner hash join when the build side was empty?52019-12-05 21:08
2019-11-22 11:33QuestionWhat does BmkToPage mean in an execution plan?72019-11-22 11:32
2019-11-21 20:34QuestionHow Do Partial Aggregates Calculate Their Memory Grants?52019-11-21 17:07
2019-11-18 12:17Meta QuestionWhat default fonts should we use on TopAnswers/databases?42019-11-18 10:41
2019-11-20 05:47QuestionAfter upgrading to SQL Server 2019, function throws “insufficient memory” error82019-11-17 12:22
2019-11-09 11:03QuestionAre repeated expressions calculated more than once?72019-11-06 13:35
2019-09-18 17:15QuestionСardinality estimation of partially covering range predicates32019-09-18 12:27
2019-09-03 05:42QuestionWhy doesn't this recursive CTE with a parameter use an index when it does with a literal?22019-09-02 06:29
2019-08-31 11:06QuestionInserting with implicit type conversion causes warning for cardinality estimates32019-08-30 19:58
2019-08-02 13:46QuestionConstant Scan spooling32019-08-02 00:28
2019-07-30 01:11QuestionWhy does this RX-X lock not appear in Extended Events?32019-07-29 16:20
2019-07-17 20:47QuestionWhat does SQL Server do for a hash aggregate bailout?42019-07-17 20:47
2019-07-04 15:33QuestionImplicit conversion between decimals with different precisions22019-07-04 15:02
2019-07-01 15:59QuestionSQL Server error 242 with ANSI datetime12019-07-01 15:03
2019-06-22 11:20QuestionIndex Seek scanning whole table dependent on parameter value32019-06-21 12:24
2019-06-20 05:32QuestionCan we put an equal sign (=) after aggregate functions in Transact-SQL?22019-06-20 05:24
2019-06-19 00:33QuestionUpdate Intersect hangs02019-06-18 19:24
2019-06-05 20:46QuestionCROSS APPLY produces outer join42019-06-05 14:08
2019-05-31 11:33QuestionWhat is the purpose of this Uniq1002 column in this index scan?52019-05-30 19:25
2019-05-30 08:53QuestionSelf referencing scalar function nesting level exceeded when adding a select52019-05-29 11:52
2019-03-22 06:42QuestionWhy does a simple loop result in ASYNC_NETWORK_IO waits?32019-03-22 04:21
2019-02-26 04:10QuestionWhy is a temp table a more efficient solution to the Halloween Problem than an eager spool?32019-02-26 01:27
2019-02-25 10:45QuestionSingle-row INSERT…SELECT much slower than separate SELECT32019-02-25 10:22
2019-02-04 15:25QuestionWhat is a scalable way to simulate HASHBYTES using a SQL CLR scalar function?32019-02-03 16:57
2019-02-01 12:15QuestionWhy is the auto created statistic on this column empty?02019-02-01 09:02
2019-01-28 12:15QuestionWhen does SQL Server warn about an Excessive Memory Grant?32019-01-28 12:15
2019-01-05 10:11QuestionWhen can SARGable predicates be pushed into a CTE or derived table?22019-01-02 18:16
2018-10-03 11:08QuestionWhy is a scan faster than seek for this predicate?32018-10-03 03:26
2018-09-01 14:22QuestionWhy doesn't join elimination work with sys.query_store_plan?22018-09-01 14:22
2018-08-31 15:26QuestionActual rows read in a table scan is multiplied by the number of threads used for the scan02018-08-31 14:22
2018-08-21 08:32QuestionBad row estimate following Compute Scalar operator in plan22018-08-21 08:04
2018-08-16 21:58QuestionWhy does changing the declared join column order introduce a sort?32018-08-16 11:58
2018-08-04 11:52QuestionAre duplicates in Read Commited standard behaviour?22018-08-03 16:49
2018-08-04 11:24QuestionIs sql_variant compatible with First Normal Form (1NF)?02018-07-27 15:20
2018-07-03 09:00QuestionIndex Seek Operator Cost12018-07-03 09:00
2018-06-09 03:03QuestionSQL Server splits A <> B into A < B OR A > B, yielding strange results if B is non-deterministic42018-06-08 09:53
2018-05-29 11:17QuestionWhy am I not getting minimal logging when inserting to indexed tables32018-05-25 07:39
2018-05-05 10:39QuestionIn SQL Server, is parallelism per operator, or something else?32018-05-04 00:53
2018-03-27 15:19QuestionWhat is the StatementParameterizationType plan attribute?12018-03-27 15:19
2018-02-27 13:44QuestionWhen is the SQL Server database ready to accept queries?22018-02-27 11:22
2017-10-18 07:16QuestionWhy does truncating a temp table at the end of the stored procedure that creates it free tempdb space faster?42017-10-17 13:19
2017-10-03 15:14QuestionHow do you create a view with SNAPSHOT_MATERIALIZATION in SQL Server 2017?12017-10-03 14:47
2017-10-01 06:21QuestionIs there a way to prevent Scalar UDFs in computed columns from inhibiting parallelism?32017-09-30 16:40
2017-09-10 20:12QuestionUnique index updates and statistics row modification counters32017-09-10 20:12
2017-08-04 15:17QuestionWhy does the READPAST hint cause indexed views to be ignored?12017-08-03 23:18
2017-08-02 08:57QuestionForcing Flow Distinct32017-08-01 19:45
2017-07-29 12:52QuestionWhy does performing a delete on my partitioned view result in a Clustered Index Insert?22017-07-29 00:21
2017-07-25 17:03QuestionStrange behaviour with sample sizes for statistics updates12017-07-21 14:46
2017-06-16 00:47QuestionWhy can it take up to 30 seconds to create a simple CCI rowgroup?22017-06-07 15:49
2017-05-18 14:09QuestionWhy doesn't this query use an index spool?22017-05-18 13:47
2017-05-09 20:04QuestionWhy am I getting “Snapshot isolation transaction aborted due to update conflict”?22017-05-09 13:46
2017-04-23 16:55QuestionWhy does a subquery reduce the row estimate to 1?42017-04-21 15:33
2019-11-17 12:54QuestionWhy does TSQL return the wrong value for POWER(2.,64.)?32017-03-31 20:29
2017-03-14 11:10QuestionUnion implemented with Hash Match operator22017-03-14 01:17
2017-02-20 16:07QuestionWhy does my SELECT DISTINCT TOP N query scan the entire table?52017-02-20 14:39
2016-12-28 13:20QuestionDoes SQL Server cache the result of a multi-statement table-valued function?22016-12-28 13:20
2019-11-27 19:21QuestionWhere is Read Committed insufficient?22016-12-05 09:56
2019-11-24 10:13QuestionAuthoritative source that <> and != are identical in performance in SQL Server42016-11-17 22:39
2016-10-28 16:50QuestionCardinality Estimate for LIKE operator (Local Variables)22016-10-25 17:57
2017-04-06 22:16QuestionCardinality Estimation for >= and > for intra step statistics value22016-09-01 09:18
2019-11-24 10:28QuestionIs there any benefit to SCHEMABINDING a function beyond Halloween Protection?42016-06-04 06:35
2016-05-08 14:07QuestionLogical reads different when accessing the same LOB data42016-05-08 14:07
2016-04-22 10:10QuestionWhere do this Constant Scan and Left Outer Join come from in a trivial SELECT query plan?22016-04-22 09:46
2016-04-11 09:59QuestionSQL Server sample Update of Statistics misses highest RANGE_HI_KEY on ascending key column12016-04-11 08:42
2016-03-18 03:08QuestionSARGable WHERE clause for two date columns12016-03-16 20:16
2019-11-26 16:07QuestionHow to reset statistics after UPDATE STATISTICS … WITH ROWCOUNT32016-02-27 15:56
2019-11-26 09:14QuestionCannot execute as the database principal because the principal “dbo” does not exist12015-08-19 10:30
2019-11-25 23:43Questionsp_cursoropen and parallelism12015-07-09 13:23
2015-04-21 03:13QuestionSQL Server unpredictable select results (dbms error?)72015-04-20 11:59
2019-11-25 22:55QuestionHow does SQL Server's optimizer estimate the number of rows in a joined table?12015-04-02 16:46
2019-11-25 13:54QuestionIn SQL Server, can I guarantee an order without an explicit ORDER BY clause when an index seek is forced on a table with only a clustered index?12014-12-17 18:30
2019-11-24 11:04QuestionExcessive sort memory grant22014-12-17 10:12
2014-12-11 19:08QuestionAre actual stored procedures the only mechanism that implements temp table caching?32014-12-11 18:06
2019-11-25 12:08QuestionGet minimal logging when loading data into temporary tables12014-12-11 11:28
2014-11-28 06:59QuestionHow to recursively find gaps where 90 days passed, between rows02014-11-23 20:24
2019-11-25 10:16QuestionWhy is cost threshold for parallelism ignored?22014-11-05 19:35
2019-11-25 10:12QuestionAre RANK() and DENSE_RANK() deterministic or non-deterministic?22014-09-25 13:48
2019-11-25 10:07QuestionSwitching Data In Fails with “allows values that are not allowed by check constraints or partition function on target table”62014-09-10 16:13
2014-06-06 04:51QuestionJoining on same table without duplicating data in a field or using c#32014-06-05 19:40
2014-05-15 13:36QuestionGiving server-role to login breaks stored procedures72014-05-14 19:25
2014-05-10 19:38QuestionWhat is the correct way to ensure unique entries in a temporal database design?12014-05-09 17:12
2014-05-09 20:04QuestionGet streak count and streak type from win-loss-tie data02014-05-08 06:05
2019-11-23 08:10QuestionWhy does query error with empty result set in SQL Server 2012?22014-02-13 18:36
2019-11-23 08:21QuestionMoving primary key constraint from one index to another12013-12-18 18:38
2019-11-23 08:16QuestionWhy does SQL Server require the datatype length to be the same when using UNPIVOT?22013-12-03 14:11
2013-10-29 06:40QuestionGROUP BY with MAX versus just MAX22013-10-28 10:09
2013-10-28 00:39QuestionIndex on Persisted Computed column needs key lookup to get columns in the computed expression22013-10-24 08:31
2019-11-20 12:21QuestionLIKE uses index, CHARINDEX does not?32013-07-24 11:51
2019-11-24 10:18QuestionMERGE a subset of the target table52012-12-17 21:17
2019-11-26 10:47QuestionHow (and why) does TOP impact an execution plan?22012-09-24 19:08
2012-09-06 04:04QuestionOptimizer not choosing index union plan62012-09-06 02:27
2011-09-19 18:43QuestionDoes SQL Server read all of a COALESCE function even if the first argument is not NULL?52011-09-19 15:06