sql cte performance

. Room number andAcquisition Time>='2013-11-6 0:00:00' andAcquisition Time'2013-11-7 0:00:00') Workaround, create a memory table in SQL, first identify the part, and then use the first part of the results to query the final result. It can be checked in seconds. SET STATISTICSIo onDBCCDropcleanbuffers--Turn off cachingDBCCFreeproccache--Turn off cachingSELECTT.* frommeasure_heat TWHERECommunity number=' -' andAcquisition Time=( SELECT min(Acquisit

Original http://www.cnblogs.com/BoyceYang/archive/2013/06/15/3138142.html Read navigation 1. Overview 2.RulesLogic Database Design 3.EnableDesign with efficient Indexes 4.EnableEfficient Query Design 5.EnableLow performance analysis with technology 6. Summary 1. Overview This is the most effective way to optimize SQL server performance by find

Tags: time interval fetch number release operation rebuild file GIF world loadThe IO performance of SQL Server is affected by the IO latency of the physical disk and the IO operations performed internally by SQL Server. When monitoring disk performance, the primary measure (metric) is IO latency, which is the time dela

I used to pursue new things, and found the foundation is the most important, this year's main goal is to master SQL query and SQL performance optimization.This series of "T-SQL Fundamentals" is primarily a summary of the T-SQL Foundation."T-

Label:The IO performance of SQL Server is affected by the IO latency of the physical disk and the IO operations performed internally by SQL Server. When monitoring disk performance, the primary measure (metric) is IO latency, which is the time delay in creating an IO request from application to disk to complete the IO

SQL Server focuses on optimization of Stored Procedure performance, data compression, and page compression to improve IO performance (I ). Preface The SQL Server basic series is not over yet, And the last point is not written, and will continue later. Some school friends asked me when I began to write the

parameter mode, what problems the automation parameters will bring, and how to solve them.The problem itself is very simple, if you do not notice still occasionally will appear confused. Off Topic Have a little feeling very deep, that is, more and more practical problems, have to have theoretical knowledge to support,But it is often theoretically said that the situation does not appear frequently or even if there is no attention, there is time to neglect some theoretical knowledge.For the prob

very deep, that is, more and more practical problems, have to have theoretical knowledge to support,But it is often theoretically said that the situation does not appear frequently or even if there is no attention, there is time to neglect some theoretical knowledge.For the problems encountered, if you really want to find out, still have some theoretical knowledge to do the groundwork. Many times, often after encountering problems, recalled once good seems to have seen this aspect of theoretica

Label:A colleague with my feedback he has encountered a SQL performance problem, he said that the full table only 69 records, client execution spent more than two minutes, it is not scientific. Want me to analyze the reason and solve. I have constructed a case based on a similar table structure, and the test is as followsThis table has 13800KB (that is, 13M multi-size), because the table saves the picture t

Label:The optimization of SQL statements is to convert poorly performing SQL statements into the same performance SQL statements with the same purpose.AI automatic SQL optimization uses AI technology to automatically rewrite SQL s

very deep, that is, more and more practical problems, have to have theoretical knowledge to support,But it is often theoretically said that the situation does not appear frequently or even if there is no attention, there is time to neglect some theoretical knowledge.For the problems encountered, if you really want to find out, still have some theoretical knowledge to do the groundwork. Many times, often after encountering problems, recalled once good seems to have seen this aspect of theoretica

MySQL batch SQL insert performance optimization details, mysql Performance Optimization For some systems with a large data volume, the database faces problems in addition to the low query efficiency, but also the long data warehouse receiving time. Especially for the report system, the time spent on data import may be several hours or dozens of hours every day. T

The optimization of SQL statements is to reduce the performance of SQL statementsConversionSQL statements with the same performance as the target. Artificial Intelligence automatic SQL optimization is the use of artificial intelligence technology, automatic rewriting of

This article explains how to split an SQL statement with one or more left JOIN or right join into multiple SQL statements. MySQL query efficiency is very low, especially large data, and high concurrency, the index can not solve the problem, the best way is to split the SQL statement into multiple single table query SQL

Original: SQL Server performance Optimization nolock, greatly improve database query performanceThe company database grows with time, the data is more and more, the query speed is also more and more slow. Into the database to see a bit, hundreds of thousands of of the data, the query is really time-consuming.To improve the query performance of

The company database grows with time, the data is more and more, the query speed is also more and more slow. Into the database to see a bit, hundreds of thousands of of the data, the query is really time-consuming.To improve the query performance of SQL, we generally consider the index as the first consideration. In fact, in addition to the establishment of the index, when we are under the

:16TAB1 small, TAB2 billion level above, two weeks data in tens of millions of.Lan Hua Main 16:13:22Ok.Orchid Island Main 16:16:29So change the SQL:with T1 as (Select count (t.c1), t.c1,t.c2,t.c3,t.c4,t.c5From Tab1 twhere T.c2 not in (' Val1 ', ' val2 ', ' val3 ', ' val4 ', ' VAL5 ')and C1 is not NULLGroup by T.C1, T.C2,T.C3,T.C4,T.C5)Select T1.c1,t1.c2,t1.c3,t1.c4,t1.c5from T1Where NOT EXISTS (Select/*+ Use_hash (m,n) */M.C1, M.C2,M.C3,M.C4,M.C5from T1 m,tab2 Nwhere N.c2 > Sysdate-14and m.c1 =

number of the search results As (Ceiling () (Row_number () over () -1)/@pagesize as int) as pageindex,* from TableName where ...)SELECT * Fromcte_temp where pageindex= @pageindex-1; Conclusion: TOPN is the fastest in a small number of pages, if it is below 10 page, you can consider it, CTE and temporary table time is very stable, CTE consumes more time than the temporary table, but does not cause the gr

tools for the corresponding pages. 6. Avoid high-cost operations with memory cache PHP often plays an important role in retrieval and data analysis, which can lead to performance degradation. In fact, some operations are completely unnecessary, especially from the database repeatedly retrieving some commonly used static data. Consider the short-term use of Memcached extension to cache data. Memcached's extended cache works with the libmemcached libra

after you've processed historical data and report data, then add these new hardware, such as faster CPUs and hard drives, larger memory, and so on, but add new hardware postscript to modify your SQL Server configuration to accommodate these new hardware, such as opening/ 3G switch to use more memory. Scale out when scaling the up does isn't suffice or is cost-prohibitive. Use horizontal expansion When you are still not satisfied with the upward exp