sql for data analysis udacity

deliberately added some other content, help friends to make a transition.Because index fragmentation analysis involves some knowledge of page splitting, page splitting occurs when the data on a page fills up without extra space for the new data, and adding new data to a page that already fills the

Server one, defining a data source view in an Analysis Services project 1. Create an Analysis Services project based on the template BIDS (Business Intelligence Development Studio) uses templates to create different types of projects, and the Analysis Services project is one of the templates, and the templates are cust

performance problems. In terms of performance, each item shown below is not ideal. Index or table scans (index or table scan): it may mean better or additional indexes are required. Bookmark lookups: you can modify the current clustered index and overwrite the index to limit the number of fields in the SELECT statement. Filter: Remove any function used in the WHERE clause. do not include a view in an SQL statement. Additional indexes may be required.

four SQL is the same as the execution time after the Oracle analysis, but from the Oracle shared memory SGA, it can be concluded that Oracle will analyze each SQL and consume shared memory. If you write the SQL string and format exactly the same, then Oracle will only parse once, and the shared memory will only leave

)The results and execution time of the preceding four sqls are the same after ORACLE analysis, but the principle of shared memory SGA from ORACLE is as follows,It can be concluded that ORACLE will analyze each SQL statement and occupy the shared memory,If the SQL string and format are completely the same, ORACLE only analyzes the

execution plans. 　　 Clear Cache During performance analysis, you sometimes need to clear the cache for the next analysis. SQL Server provides some tools to clear cache performance data. Use the following statement to complete these tasks. Use the following statement to clear the global cache: Dbcc dropcleanbuffers; C

). Trim.toint)) 5.people.registerastable (" People ") 6.val teenagers = SQL ("Select name from people WHERE the age >= and the Age The first two sentences of the program 1 and 2 generate SqlContext, import SqlContext The following all, that is, run sparksql context.Program 3, 42 sentence is the Load Data Source Register tableThe 6th sentence is the real entrance, is the

Basic introductionProgram developers often have to analyze the program log, including their own print logs and other software used to print the log, such as Php,nginx logs, Linux environment analysis logs have some built-in commands to use, such as Grep,sort,uniq,awk, the most powerful of which is awk, exists as a small text-processing language, but because it is a language that is powerful, it is not so convenient to use at the command line because A

SQL Server performance analysis query table space and available space Posted @ zping read (58) | comment (0) Edit Interval between querying long transactions and SQL Execution Posted @ zping read (110) | comment (0) Edit Query execution information of SQL Server Stored Procedures Posted @ zping read (126) | comment

execution time of the preceding four sqls are the same after Oracle analysis, but the principle of shared memory SGA from Oracle is as follows, it can be concluded that Oracle will analyze each SQL statement once and occupy the shared memory. If the SQL string and format are completely the same, Oracle will analyze it only once, the shared memory also leaves onl

same, ORACLE will analyze it only once, shared Memory also leaves only one analysis result. This not only reduces the time required to analyze SQL statements, but also reduces duplicate information in shared memory. ORACLE can also accurately count the execution frequency of Oracle SQL statements. Recommended Solution: Make sure that the query characters are ide

; The table has been changed. Used time: 00: 15: 58.85 SQL> exec dbms_stats.gather_table_stats (user, 't', cascade => true ); The PL/SQL process is successfully completed. Used time: 00: 00: 36.87 SQL> select bytes/1024/1024, blocks from dba_segments where wner = 'sys 'and segme Nt_name = 'T '; BYTES/1024/1024 BLOCKS ------------------------- 256 32768 Us

will delete all the databases. Five rows of data are deleted after the execution is successful: Add another row of data: The last line of data is updated: The query is displayed again: So far, the basic SQL Syntax Parsing and implementation have ended. For GroupBy, multi-table, view, function, and so on, it is be

algorithm, the previous article we have introduced, when we face a bunch of data and to be based on a certain purpose to the data mining, feel that we do not know or choose the appropriate algorithm in DM, At this point we apply the Microsoft Neural Network analysis algorithm, and when we analyze the rules with the Microsoft Neural Network

storage engineer is not a professional DBA, the memory usage of the SQL Server database server may not be too familiar with this question can be understood.Because the storage used by the database server is a high-performance SAN storage, storage is available as a service, with n multiple servers in common,Other servers do not have disk requests, it is unlikely that a single server will appear as a "storage failure" is simply identified as a storage

Label: --statistics on the amount of data per day for March Select Count(*), substr (T.date,1,Ten) from TableTwhereT.date like '2010-03%' Group bySUBSTR (T.date,1,Ten) ; --statistics from May to 1 September-June 29 Data Volume SELECTSUBSTR (A.feed_publish_time,1,Ten) as 'Date',Count(*) as 'Medical Talk Number' fromXm_feed AWHEREA.feed_publish_timebetween '2015-05-19 00:00:00' and '2015-06-29 23:59:59' GR

Tags: good protected register plain should and syntax LAN execution plan/** Spark SQL Source Analysis series Article */ Since last year, Spark's Submit Michael Armbrust shared his catalyst, more than 1 years, spark SQL contributor from a few people to dozens of people, and the development speed is extremely rapid, the reason, personally think there are the follow

/** Spark SQL Source Code Analysis series Article */Since last year, spark Submit Michael Armbrust shared his catalyst, to now more than 1 years, spark SQL contributor from several people to dozens of people, and the development speed is extremely rapid, the reason, personally feel there are 2 points:1. Integration: The SQL