Little script for finding tables for which dynamic sampling was used
You can always download latest version here: http://github.com/xtender/xt_scripts/blob/master/dynamic_sampling_used_for.sql Current source code: col owner for a30; col tab_name for a30; col top_sql_id...
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Just a couple of screenshots of sqlplus+rlwrap+cygwin+console
I previously wrote that I peeped the idea about showing the session information in terminal title from Timur Akhmadeev’s screenshots, and Timur wrote: I’m using (a bit modified) Tanel Poder’s login.sql...
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Simple Android Oracle client
I am happy to announce, that I’ve just published my first android app – Simple oracle client for android! Since this is only the first version, I’m sure that it contains various UI bugs, so I’ll wait...
View ArticleINDEX FULL SCAN (MIN/MAX) with two identical MIN()
I’ve just noticed an interesting thing: Assume, that we have a simple query with “MIN(ID)” that works through “Index full scan(MIN/MAX)”: SQL> explain plan for 2 select 3 min(ID) as x 4 from tab1 5...
View Articleselect * from table where rownum=1
I never thought I would have to optimize so simple query as select col1, col2, col4, col7 from table where rownum=1 (even though I read recently “SELECT * FROM TABLE” Runs Out Of TEMP Space) But a few...
View ArticleEasy quiz: rownum < NaN
As you know, NaN is a “Not a Number”. How do you think, what would be the result of the following query? (0f/0 == NaN) select count(*) cnt from dual where rownum < 0f/0; Spoiler:: Answer...
View Article12c: Little test of “TABLE ACCESS INMEMORY FULL” with count stopkey
The table has 9M rows: SQL> with function f return int is 2 begin 3 for r in (select value from v$mystat natural join v$statname where name like 'IM scan rows') loop 4 dbms_output.put_line(r.value);...
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Little quiz: Ordering/Grouping – Guess the output
How many times have you guessed the right answer? 1 select * from dual order by -1; select * from dual order by 0; [collapse] 2 select * from dual order by -(0.1+0/1) desc; select 1 n,0 n,2 n,0 n,1 n...
View ArticleSQL*Plus tips #7: How to find the current script directory
You know that if we want to execute another script from the current script directory, we can call it through @@, but sometimes we want to know the current path exactly, for example if we want to spool...
View ArticleA function gets called twice if the result_cache is used
Recently I showed simple example how result_cache works with non-deterministic functions and observed strange behaviour: a function gets fired once in the normal query, but twice with the result_cache...
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RESULT_CACHE: run-time dependency tracking
As you know, since 11.2 “relies_on” clause was deprecated and oracle tracks dependencies at runtime now. Test function and tables create or replace function f_without_deps(p_tab varchar2) return...
View Article12c: New SQL PLAN OPERATIONS and HINTS
This post is just a compilation of the links to other people’s articles and short descriptions about new SQL PLAN OPERATIONS and HINTS with a couple little additions from me. th.c_operation_name {...
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Very simple oracle package for HTTPS and HTTP
I don’t like to import certificates, so i cannot use httpuritype for HTTPS pages and I decided to create package which will work with https as http. It was pretty easy with java stored procedures...
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Oracle Database Developer Choice Awards: Up-Voters list
It’s very easy to get and analyze voters list using my new XT_HTTP package We can get up-voters list by the URL:...
View ArticleOracle package for HTTPS/HTTP[version 0.2]
A couple days ago i created simple package for HTTPS/HTTP, but I’ve decided now to improve it: Timeout parameter – it would be better to control connection time; Simple page parsing with PCRE regular...
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Thanks to all #odevchoice voters!
And special thanks to all the great people who voted for me! I want to list all voters for all nomenees in one page: http://orasql.org/odevchoice/all-the-voters.html The query (using xt_http of course...
View ArticleWINDOW NOSORT STOPKEY + RANK()
Recently I found that WINDOW NOSORT STOPKEY with RANK()OVER() works very inefficiently: http://www.freelists.org/post/oracle-l/RANKWINDOW-NOSORT-STOPKEY-stopkey-doesnt-work The root cause of this...
View Article8 queens chess problem: solution in Oracle SQL
This is just another solution of this problem for a chessboard, but you can choose any size of the checkerboard: with t as (select level i, cast(level as varchar2(1)) c from dual connect by...
View ArticleHow even empty trigger increases redo generation
Very simple example: Test case set feed on; -- simple table: create table xt_curr1 as select level a,level b from dual connect by level<=1e4; -- same table but with empty trigger: create table...
View Articlerow pieces, 255 columns, intra-block row chaining in details
You may know about Intra-block row chaining, that may occur when the number of columns in a table is more than 255 columns. But do you know that intra-block chaining works with inserts only? not...
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