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PreparedStatement are very slow when table is "default collation ebcdic"

Vincent B.Mar 6 2024

Hello,
when I execute a SELECT via a PreparedStatement, on a table being "DEFAULT COLLATION EBCDIC", with a large volume of data (several million rows), I notice that the query is very slow.
For example, on a table with 400 million rows, the SELECT of a single row takes 11 minutes!
If I make an extract from this table (3 million rows), I get the following execution times:
- 5s (preparedStatement to table with COLLATION)
- 0.2s (same query, but Statement, to table with COLLATION)
- 0.006s (preparedStatement to table without COLLATION)

Tested in several ways: with JDBC drivers ojdbc7 (version 12.1.0.2.0) and ojdbc8 (19.21.0.0.0), from a Windows workstation and from a SLES15 server, to an Oracle database 19.17.0.0.0 or 19.21.0.0.0. Statistics are up to date on all tables. The performance problem was observed in all configurations.

We ran the test in pure SQL, and found that the execution plan is not the same via the JDBC driver:

via JDBC (index range => generate filter access):

-----------------------------------------------------------------------------------------------------
| Id | Operation | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time |
-----------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | 24 (100)| |
|* 1 | TABLE ACCESS BY INDEX ROWID BATCHED| TESTEBCDIC | 1 | 137 | 24 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | ITESTEBCDIC1 | 1 | | 24 (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

1 - filter((NLSSORT("LIB6",'nls_sort=''EBCDIC''')=NLSSORT(:5,'nls_sort=''EBCDIC''') AND
NLSSORT("LIB7",'nls_sort=''EBCDIC''')=NLSSORT(:6,'nls_sort=''EBCDIC''') AND
NLSSORT("LIB10",'nls_sort=''EBCDIC''')=NLSSORT(:9,'nls_sort=''EBCDIC''') AND
NLSSORT("LIB8",'nls_sort=''EBCDIC''')=NLSSORT(:7,'nls_sort=''EBCDIC''') AND
NLSSORT("LIB4",'nls_sort=''EBCDIC''')=NLSSORT(:3,'nls_sort=''EBCDIC''') AND
NLSSORT("LIB3",'nls_sort=''EBCDIC''')=NLSSORT(:2,'nls_sort=''EBCDIC''')))
2 - access("LIB2"=:1 AND "LIB5"=:4 AND "LIB9"=:8)
filter(("LIB5"=:4 AND "LIB9"=:8))

SQL (correct access):

---------------------------------------------------------------------------------------------
| Id | Operation | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time |
---------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | 1 (100)| |
| 1 | TABLE ACCESS BY INDEX ROWID| TESTEBCDIC | 1 | 313 | 1 (0)| 00:00:01 |
|* 2 | INDEX UNIQUE SCAN | ITESTEBCDIC1 | 1 | | 1 (0)| 00:00:01 |
---------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

2 - access("LIB2"=:CLE2 AND "TESTEBCDIC"."SYS_NC00011$"=NLSSORT(:CLE3,'nls_sort=''
EBCDIC''') AND "TESTEBCDIC"."SYS_NC00012$"=NLSSORT(:CLE4,'nls_sort=''EBCDIC''') AND
"LIB5"=:CLE5 AND "TESTEBCDIC"."SYS_NC00013$"=NLSSORT(:CLE6,'nls_sort=''EBCDIC''')
AND "TESTEBCDIC"."SYS_NC00014$"=NLSSORT(:CLE7,'nls_sort=''EBCDIC''') AND
"TESTEBCDIC"."SYS_NC00015$"=NLSSORT(:CLE8,'nls_sort=''EBCDIC''') AND
"LIB9"=TO_DATE(:CLE9,'YYYY-MM-DD') AND "TESTEBCDIC"."SYS_NC00016$"=NLSSORT(:CLE10,'nl
s_sort=''EBCDIC'''))

Thanks for help!

Comments

Sdhamoth-Oracle Oct 16 2024

Check the error reported in “Control panel→System and Securities→Administrative Tools→Event Viewer” under Windows Log→Application.

How did you set the Instant Client path in PATH? In command prompt?

If you have set it in a command prompt, then make sure you start that command prompt as administrator (i.e. opening it by right clicking on command prompt icon and select “run as administrator” from popped context menu). Also, you should start ODBC data source administrator by executing “odbcad32” from that command prompt. Have you?

pczurak-JavaNet Oct 16 2024

Yes I started the cmd as run as Administrator.

I am using ODBC 64 bit not 32 bit.

I set the path using Windows UI (System properties), and if I open a cmd window and type set I can see the correct path.

starting “odbcad32” from the command line did not help.

I tried the same process on a different computer and got the same results.

Sdhamoth-Oracle Oct 16 2024

odbcad32 is for ODBC 64 bit on Windows x64 versions. You need to start odbcad32 from syswow64 directory to configure ODBC 32 bit on Windows x64 versions.

Have you checked the Application error logs in Event viewer? Did you find any error related to your ODBC application?

pczurak-JavaNet Oct 16 2024

I am running the 64bit version, if I start odbcad32 from syswow64 it starts the 32bit version.

There are no errors in the Event Viewer.

pczurak-JavaNet Oct 17 2024

I have tried basic driver version 19.24, but when I click on the Test button, I get the following error:

---------------------------
Testing Connection
---------------------------
Unable to connect
SQLState=S1000
[Oracle][ODBC][Ora]ORA-12504: TNS:listener was not given the SERVICE_NAME in CONNECT_DATA

---------------------------
OK
---------------------------

Sdhamoth-Oracle Oct 17 2024

Looks like the service name is missing in your connection string.

Here is a sample of connection string:

sales=
(DESCRIPTION=
(ADDRESS= (PROTOCOL=tcp)(HOST=sales-server)(PORT=1521))
(CONNECT_DATA=
(SERVICE_NAME=sales.us.acme.com)))
The part that is highlighted with bold characters seems to be missing in your connection string. Fix it.

pczurak-JavaNet Oct 17 2024

This is what I am using.

JDEPRD =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = testoda0)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = jdeprd.test.com)
)
)

Sdhamoth-Oracle Oct 17 2024

Are you able to connect to your database using SQL*Plus?

pczurak-JavaNet Oct 17 2024

No:

F:\instantclient_23_5>sqlplus

SQL*Plus: Release 19.0.0.0.0 - Production on Thu Oct 17 07:55:39 2024
Version 19.24.0.0.0

Copyright (c) 1982, 2024, Oracle. All rights reserved.

Enter user-name: testuser
Enter password:
ERROR:
ORA-12560: TNS:protocol adapter error

Enter user-name:

pczurak-JavaNet Oct 17 2024

The issue is fixed

In the ODBC Driver Configuration.

For the TNS Service Name you cannot type the name even if you type it exactly as it shows in the dropdown, you must select it from the dropdown, otherwise it won't work.

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