Tom Kyte

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These are the most recently asked questions on Ask Tom
Updated: 12 hours 25 min ago

Persuade customer to use SQLT

Mon, 2017-11-13 08:46
Hi Tom, While doing sql query tuning I came across SQLT Tool and I found it very useful. But there's one problem. Our clients (esp. client's DBAs) are not ready to allow me to use it on their production environment. I told them that it won't have ...
Categories: DBA Blogs

Last login

Mon, 2017-11-13 08:46
We are running versions 11.2.0.4 12.1 12.2. I am looking for a generic solution to capture last login date. I think the best solution would be an initial load and then maintain the information via an after logon trigger, which will contain a merg...
Categories: DBA Blogs

INACTIVE session is blocking active session

Mon, 2017-11-13 08:46
DBA is throwing information as follows 06112017:11:00:09 WELOPP@n1pv97/46581 (Session=('300,19867')Status=INACTIVE sqlid=>) blocking WELOPP@n1pv97/45876 (Session=('1803,10683') Status=ACTIVE sqlid=fp5x2quh0zpqk) f...
Categories: DBA Blogs

For Joins in Query Performance optimization

Sun, 2017-11-12 14:26
I have a query with 4 For loops puting data into temp table an then that temp table TEMPTBL_NUMBER_SEARCH is called to execute the operations in a select clause. So the problem with the 4 for loop is making it slow to 15-20 mins. Its all indside a pr...
Categories: DBA Blogs

export issue

Sun, 2017-11-12 14:26
Hi team, We are taking daily export of schema with expdp But for a few days we are continuously getting error saying - snapshot too Old. Table is a partitioned table weekly base. And the script which we are using for expdp is - expdp us...
Categories: DBA Blogs

Does the context switch account for the recursive calls

Sun, 2017-11-12 14:26
Hi Tom, Here is what i did trying to understand the enhancements of 12c. Here i was trying to understand the enhancements of WITH clause. I have created the table and compiled the below function. <code> CREATE TABLE lnd_numbers AS SELECT ...
Categories: DBA Blogs

In sql how can I update a value , and then reuse the updated value and re-update it

Sun, 2017-11-12 14:26
Hi Gurus I need to write in SQL something which previously was done in PL/SQL if possible. I have a Invoice Line Description e.g. 'ABC Mon Tue' for which I need to translate certain words. I also have a lookup(fnd_lookups) which stores the...
Categories: DBA Blogs

Versioning Data Model

Sat, 2017-11-11 01:46
Hi AskTom team, I'd like your ideas about the data model design and/or Oracle features that I could take advantage of to achieve the design goals described below. <u>Background:</u> I'm in the early stages of designing a data model for a bra...
Categories: DBA Blogs

Union all query missing lines

Sat, 2017-11-11 01:46
Hello Tom and Tom, Linked live sql shows a condensed and "moved-to-dual" query we are using with a far resemblance on our database. It's a couple of nested "union all" statements, where we would expect the outermost union (UNION2) to deliver the u...
Categories: DBA Blogs

Grant select on a View with grant option does not work

Sat, 2017-11-11 01:46
Hi, I have Schema_1 that owns table_1, table_2, table_3. Schema_1 creates View_1 using table_1, Schema_1 Creates View_2 using table_2, Schema_1 Creates View_3 using table_3. Schema_2 Creates View_4 using View_1, View_2 and View_3. Then ...
Categories: DBA Blogs

Identify patterns and create groups

Fri, 2017-11-10 07:35
I have data that looks like this: <code>create table t (a varchar2(30), b date); insert into t values (NULL,TO_DATE('2003/05/03 16:02:44', 'yyyy/mm/dd hh24:mi:ss')); insert into t values (NULL,TO_DATE('2003/05/03 17:02:44', 'yyyy/mm/dd hh24:mi...
Categories: DBA Blogs

optimistic search for most recent records

Fri, 2017-11-10 07:35
Hi, I have very large table which constantly grows. The search is executed by ID column, which is part of PK. <code> create table TEST ( ID varchar2(20) primary key, VALUE varchar2(20), CREATED_TS timestamp default := systimes...
Categories: DBA Blogs

selecting table column based on lookup table

Fri, 2017-11-10 07:35
Hi I am trying to get columns from a table only if that column value is set as "YES" in another lookup table. Please help me to get the query for the same. I have a lookup table like this: create table cust_bug_lookup(Title varchar2(100), ...
Categories: DBA Blogs

Partitioned table performance

Fri, 2017-11-10 07:35
We have a partitioned table with more than 200 columns and 60 indexes. It has 10 foreign keys with related indexes and the remaining indexes are global style. It partitioned in a yearly basis and sub-partitioned in company. Now, we're have perfor...
Categories: DBA Blogs

there is a Bug using MERGE and DUAL together

Fri, 2017-11-10 07:35
Consider please the follwing simple table: <code>create table table_1 (c1 varchar2(100), c2 varchar2(100));</code> If we apply the following MERGE command now (attend please the WHERE clause), we get: <code> merge into table_1 tb using (se...
Categories: DBA Blogs

How to hire a Lead Oracle DBA

Fri, 2017-11-10 07:35
Hi I'm a Junior Oracle DBA in the new company that I joined in. Our Lead Oracle DBA resigned and my company is screening for new applicants. The boss of our department might ask me to interview the potential Oracle Lead DBA candidate and a...
Categories: DBA Blogs

Formatting negative values to sort correctly but keep the formatting

Fri, 2017-11-10 07:35
I have an old and a new query. I need help with the new one. The old query works fine. For the new one, I can't seem to find a way to format two columns (latitude and longitude, I need 6 digits after the decimal) in such a way as they sort correctly....
Categories: DBA Blogs

Oracle Block Size

Thu, 2017-11-09 10:06
Hi Tom, I would be very grateful if you could share your thoughts on Oracle block size. "rule of thumb" is Oracle Database block sizes (2 KB or 4 KB) for online transaction processing (OLTP) or mixed workload environments and larger block size...
Categories: DBA Blogs

Where clause mix of AND and OR with()

Thu, 2017-11-09 10:06
Hello, I need to mix and or in where cluse: like: and con1 and (con2 or con3 or con4)... t_where := t_where || ' and a.field1 = ''' || l_1 || '''' || ' ( ' || 'a.field2 = ''' || l_2 || '''' || ' or ' || ......
Categories: DBA Blogs

sql loader and date

Thu, 2017-11-09 10:06
hi!!! i am using sqlloader, i have a table T in my database T (empno, start_date date, resign_date date) my data file has data like this (date format IN THE DATAFILE is 'YYYYMMDD') 1, 19990101,20001101 2, 19981215,20010315 3, 19950520...
Categories: DBA Blogs

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