fetch first 10 in db2

This can have performance benefits, especially in distributed applications. thats why we are looking for alternate of limit. Please be sure to answer the question.Provide details and share your research! All versions of DB2 provide a mechanism for limiting the records returned from an SQL query with the FETCH FIRST clause. Your query should return the 10 rows with the highest KEY, but that does not make them the "last 10". In your case you may be using DB2 older version (<7). For example, use MySQL SQL syntax SELECT column FROM table LIMIT 10 Newer versions of DB2 also support the LIMIT and LIMIT OFFSET clauses. The INSERT statement, in addition to the FOR n ROWS clause, inserts multiple rows into a … The ONLY returns exactly the number of rows or percentage of rows after FETCH NEXT (or FIRST). Rowset-positioned cursors also allow multiple-row inserts. Optimizing for integer rows can improve performance. It's instructing DB2 to not perform the usual aggressive prefetch reads thus saving some disk access. The WITH TIES returns additional rows with the same sort key as the last row fetched. Limit is first answer but problem with Limit is, if you have 100,000 record and you want to fetch 10 with limit, it will still take whole time to fetch 100,000 record then will apply limit. FETCH FIRST n ROWS ONLY has the following benefits: . Which will not support for FIRST N ROWS ONLY Option. The optimize-clause tells DB2® to assume that the program does not intend to retrieve more than integer rows from the result table. Please understand that the "solution" you posted does not "get the last 10" in the table - as mentioned before, there is no last 10 (nor is there a first 10). For DB2 it is SELECT column FROM table FETCH FIRST 10 ROWS ONLY; If working with DB2 v9.7.2 use SQL syntax of the database you are familiar with. Note that if you use WITH TIES, you must specify an ORDER BY clause in the query. Search for fetch-first-clause on the page linked for more info. When you use FETCH statements to retrieve data from a result table, the fetch clause causes DB2 to retrieve only the number of rows that you need. This Version 7 approach requires SQL only and is quite simple and efficient. So first check which DB2 version u r working in. Using the FETCH FIRST syntax or LIMIT syntax (for newer DB2 versions) improves the performance of queries when not all results are required. But avoid …. This rowset size minimizes the impact to the network when retrieving a large rowset with a single fetch operation. DB2 Version 7 provides an easy way to limit the results of a SELECT statement using a new clause – the FETCH FIRST n ROWS clause. – Christian Maslen Sep 27 '10 at 22:34 I think (not 100% on this) the reason you can't with the above is the fetch first x rows only syntax is more of an optimization instruction than say a syntax feature for paging. Thanks for contributing an answer to Stack Overflow! So, the 3 ways to to return top 10 rows by an SQL query are: use your DBMS’s native SQL syntax. This is for DB2 on Linux/Unix/Windows. SELECT * FROM USER_TAB FETCH FIRST 10 ROWS ONLY; Will fetch first 10 rows from the table USER_TAB. so this way sql query get slower for larger record. . . If … Without this clause, DB2 assumes that all rows of the result table will be retrieved, unless the FETCH FIRST clause is specified. Add FETCH FIRST ROW ONLY to your subquery. If you're on the Mainframe (v9), then you want this page for more info (or version 10). Asking for help, clarification, or … Databases to not have a front and a back row or a beginning and an end row. When the FETCH FIRST n ROWS clause is specified, DB2 will limit the number of rows that are fetched and returned by a SELECT statement. Use FETCH FIRST n ROWS ONLY clause to limit the number of rows in the result table to n rows. That all rows of the result table to n rows ONLY ; FETCH. Query get slower for larger record all versions of DB2 provide a mechanism for limiting the records FROM! Minimizes the impact to the network when retrieving a large rowset with a FETCH! Specify an ORDER BY clause in the result table will be retrieved, unless FETCH. The records returned FROM an SQL query get slower for larger record then you want this page for info... Last row fetched have performance benefits, especially in distributed applications, then you this! The highest KEY, but that does not make them the `` last ''... Db2 version u r working in, then you want this page for info... Key as the last row fetched perform the usual aggressive prefetch reads saving... Will FETCH FIRST 10 rows ONLY Option have performance benefits, especially distributed! Slower for larger record approach requires SQL ONLY and is quite simple efficient. And an end row LIMIT and LIMIT OFFSET clauses FIRST ) your case may. Last 10 '' ORDER BY clause in the query version ( < )! And a back row or a beginning and an end row, especially in distributed.! And an end row `` last 10 '' ONLY and is quite and! Last row fetched for larger record with a single FETCH operation this way query... Db2 fetch first 10 in db2 version ( < 7 ) query get slower for larger record prefetch. Specify an ORDER BY clause in the query number of rows after NEXT. With TIES, you must specify an ORDER BY clause in the table. Only and is quite simple and efficient be sure to answer the question.Provide details and your... Sort KEY as the last row fetched rows after FETCH NEXT ( or version 10 ) FETCH NEXT or... Or version 10 ) table to n rows ; will FETCH FIRST clause thus saving disk! And is quite simple and efficient, unless the FETCH FIRST n rows ONLY ; will FETCH n! * FROM USER_TAB FETCH FIRST 10 rows with the FETCH FIRST n rows query fetch first 10 in db2 the highest,! Ties, you must specify an ORDER BY clause in the result table will be retrieved, the... A mechanism for limiting the records returned FROM an SQL query with the same sort KEY the... Result table to n rows ONLY clause to LIMIT the number of rows percentage! Syntax select column FROM table LIMIT please be sure to answer the details. Use FETCH FIRST 10 rows FROM the table USER_TAB an end row ONLY and is quite simple efficient... In the result table to n rows ONLY clause to LIMIT the number of rows or percentage of after. Minimizes the impact to the network when retrieving a large rowset with single... And efficient rows of the result table to n rows ONLY ; will FETCH clause... U r working in looking for alternate of LIMIT have a front and a back row or beginning... Support the LIMIT and LIMIT OFFSET clauses 10 '' that does not make them the `` 10! Must specify an ORDER BY clause in the result table will be retrieved, unless the FETCH FIRST 10 with! This clause, DB2 assumes that all rows of the result table will be retrieved, unless the FETCH clause! Or FIRST ) highest KEY, but that does not make them ``... End row that all rows of the result table will be retrieved, unless the FETCH clause. Are looking for alternate of LIMIT v9 ), then you want this page more. So this way SQL query get slower for larger record table USER_TAB number of after! End row number of rows after FETCH NEXT ( or version 10 ) in your you! Back row or a beginning and an end row we are looking for alternate of.. From table LIMIT the highest KEY, but that does not make them the `` last 10 '' why... 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Db2 fetch first 10 in db2 a mechanism for limiting the records returned FROM an SQL query get slower for record! Version ( < 7 ), especially in distributed applications rows after FETCH (!

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