Tom Kyte

Hello experts, I have a UNIQUE constraint on (col1, col2) for a table. But, due to new functionality, I need a conditional unique constraint based on col 3. So something like this: if col3 = 'Val1': UNIQUE constraint on (col1, col2) else: UNIQUE constraint on (col4, col5) I'm on oracle DB 19c, and found that creating a unique index with case type helps. Can you guide me on alternative options and the pros, cons for this design. I do not want to create any new table and want the best way to achieve conditional unique constraints. Thanks

I am using version 23.1.1 and when I start up the application, it just hangs. I have no idea what to look at to even begin to diagnose the problem.

Dear Experts, Social Sign-in with Microsoft Azure/Office 365 in Oracle APEX applications is working well. I used this How-To: https://tm-apex.hashnode.dev/implementing-social-sign-in-with-microsoft-azureoffice-365-in-apex When I use the substitution variable in APEX (&APP_USER.) I get the correct name. So far so good! But we need the samAccountName for checking Authorization. I tried #samAccountName#, #sam_account_name# and #sam#. It doesn't work! :( APEX is referencing in help the site https://openid.net/specs/openid-connect-basic-1_0.html#Scopes where I found other keys ("claims"). Not all are working, for instance #sub# and #family_name# works, #preferred_username# does not work. With the help of Google I found other keys like #upn# (https://promatis.com/ch/en/build-a-secure-oracle-apex-app-with-microsoft-azure-ad-login-and-delegated-calendar-access/) which works fine and is not mentioned in the above website. But my question to you is how I get the samAccountName from Azure??? What is the correct name/key/claim? May I have to configure other things than "profile,email" in scope textfield maybe?

<code>create table add_column_default ( id number ) / insert into add_column_default ( id ) values ( 0 ) / alter table add_column_default add col1 number default 5 / insert into add_column_default ( id, col1 ) values ( 11, null ) / select * from add_column_default order by id / ID COL1 ---------- ---------- 0 5 11 2 rows selected. drop table add_column_default /</code> <b>Assumptions:</b> My understanding is that the data block is not modified during the ALTER. That is, the row with id = 0 is not updated to add a col1 value of 5. https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/ALTER-TABLE.html#:~:text=If%20you%20specify%20the%20DEFAULT,subject%20to%20the%20following%20restrictions%3A <i>"If you specify the DEFAULT clause for a column, then the default value is stored as metadata but the column itself is not populated with data. However, subsequent queries that specify the new column are rewritten so that the default value is returned in the result set."</i> Note: This used to not be the case for nullable columns in 11.2. https://docs.oracle.com/cd/E18283_01/server.112/e17118/statements_3001.htm#CJAHHIBI:~:text=When%20you%20add%20a%20column%2C%20the,a%20default%20value%20or%20NULL. <i>"When you add a column, the initial value of each row for the new column is null. ... If you specify the DEFAULT clause for a nullable column, then the default value is added to existing rows as part of this ALTER TABLE statement, and any update triggers defined on the table are fired. This behavior also results if you change a NOT NULL column with a default value to be nullable."</i> My understanding is that the data block does not store any information (not even the length byte) regarding col1 when the value is null and col1 is the last column in the table. <b>Therefore:</b> Rows inserted before the ALTER do not have col1 information. Rows inserted after the ALTER may not have col1 information (inserting null into the last fixed width column in a table). <b>Confusion/Question:</b> If both rows look the same (with respect to col1 information) in the data block, then how does Oracle know to return a col1 value of 5 for the row with id = 0 and return a col1 value of null for the row with id = 11?

Hello Sir, We're using Oracle Database 19C Enterprise edition. We're getting a XML tag in Varchar2 format. Then we're using XMLTYPE to convert that to XML. However, incase when there's special character in the XML tag it's giving a unknown special character in the output. What can we do to get the same output Sample SQL: <code>select XMLTYPE('<tag1> a''bc </tag1>') from dual;</code> Output: <code><tag1> a&apos;bc </tag1></code> Expected output: <code><tag1> a'bc </tag1></code>

Hi Dear Experts, I want to create a SQL PLAN baseline for one of the My system query in a two-node RAC 19.21. With user SYS and inside a PDB with the following commands <code>var v_num number; exec :v_num:=dbms_spm.load_plans_from_cursor_cache(sql_id => '0b3...............',plan_hash_value => 2170529430 ,fixed=>'YES');</code> It gives a successfull response. Of course, the output of the above command is returned as 0. And when I check the Plan baselines with the following command, I see that nothing new has been created: <code>select * from dba_sql_plan_baselines</code> I check with the following command and see that plan_hash_value equal to 2170529430 exists in memory: <code>select sql_id, plan_hash_value, parsing_schema_name, sql_text from v$sql where sql_id = '0b3...............';</code> What is the problem?

Hi Tom, If there is any duplications of records in a table, we know how to eliminate the duplicate rows using rowid. But is there any possibility to delete the duplicate records in a table without using rowid and rownum. my friend who is working in Oracle for arnd 4 years says that it is not possible. But i think there should be some way to do this. Pls give me some suggestion TOM. i would be thankful to you, if you can illustrate with examples. Thanks in Advance Prakash

Hello, I work as a dba and get requests from developers to create tables which we often review and sometimes change for better design and/or implementation. One of the developers recently sent a request to create a table such as the following ; table_name:t1_relation Column_names: c1_master_id_pk (foreign key to t1_master table) c1_attribute c1_value primary key all 3 columns. They explained that the data in all these columns are all non nullable and that they are all needed to uniquely identify a record. having all the columns of a table as a primary key didn't look very right to me and so I suggested we create a surrogate key and make the 3 columns unique with not null constraints on all of them. they initially said yes then came back and said to change it to be how they requested initially. I'm messaging to ask if this is proper database design and what would be the ideal way to implement this?

We have an Oracle Forms / Database application and were asked to limit User's maximum online time to 15 minutes. Following this, we set the profiles' CONNECT_TIME to 15 - this works well. How is it possible to reset this if user does any action on frontend? Maybee v$session.seconds_in_wait can help? Thanks in advance Helmut

Which PL/SQL package is primarily used for interacting with Generative AI services in Oracle Database 23ai? DBMS_AI or DBMS_ML or DBMS_VECTOR_CHAIN or DBMS_GENAI?

Hi there! I've some trouble trying to upload data from agent to OMS server, everything seems correct but: <b>emctl upload agent Oracle Enterprise Manager 24ai Release 1 Copyright (c) 1996, 2024 Oracle Corporation. All rights reserved. --------------------------------------------------------------- EMD upload error:full upload has failed: uploadXMLFiles skipped :: OMS version not checked yet. If this issue persists check trace files for ping to OMS related errors. (OMS_DOWN)</b> agent is running, OMS too, telnet from agent is: telnet myserver.com 4903 Trying 10.8.0.65... Connected to myserver.com. Escape character is '^]'. curl output: curl -vk myserver.com:4903/empbs/upload * Trying 10.8.0.65... * TCP_NODELAY set * Connected to myserver.com (10.8.0.**) port 4903 (#0) * ALPN, offering h2 * ALPN, offering http/1.1 * successfully set certificate verify locations: * CAfile: /etc/pki/tls/certs/ca-bundle.crt CApath: none * TLSv1.3 (OUT), TLS handshake, Client hello (1): * TLSv1.3 (IN), TLS handshake, Server hello (2): * TLSv1.2 (IN), TLS handshake, Certificate (11): * TLSv1.2 (IN), TLS handshake, Server key exchange (12): * TLSv1.2 (IN), TLS handshake, Server finished (14): * TLSv1.2 (OUT), TLS handshake, Client key exchange (16): * TLSv1.2 (OUT), TLS change cipher, Change cipher spec (1): * TLSv1.2 (OUT), TLS handshake, Finished (20): * TLSv1.2 (IN), TLS handshake, Finished (20): * SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384 * ALPN, server did not agree to a protocol * Server certificate: * subject: CN=myserver.com * start date: Jul 10 16:57:40 2025 GMT * expire date: Jul 9 16:57:40 2035 GMT * issuer: O=EnterpriseManager on myserver.com; OU=EnterpriseManager on myserver.com; L=EnterpriseManager on myserver.com; ST=CA; C=US; CN=myserver.com * SSL certificate verify result: self signed certificate in certificate chain (19), continuing anyway. > GET /empbs/upload HTTP/1.1 > Host: myserver.com:4903 > User-Agent: curl/7.61.1 > Accept: */* > < HTTP/1.1 200 OK < Date: Wed, 03 Sep 2025 18:53:47 GMT < X-ORCL-EM-APIGW-CONSOLIDATED-BY: apigateway < X-ORCL-EM-APIGW-ERR: 0 < X-ORACLE-DMS-ECID: 21f06e98-2895-465a-b3f3-17be919babe9-00001673 < X-ORCL-EMOA: true < X-ORCL-EM-APIGW-GUID: 6113d58d-fde2-8b19-f054-c5eee6216d13 < X-ORACLE-DMS-RID: 0 < Date: Wed, 03 Sep 2025 18:53:47 GMT < Content-Type: text/html;charset=utf-8 < X-Content-Type-Options: nosniff < X-XSS-Protection: 1; mode=block < Vary: Accept-Encoding < Content-Length: 306 < <HTML><HEAD><TITLE> Http XML File receiver </TITLE></HEAD><BODY bgcolor="#FFFFFF"> <H1>Http XML File receiver</H1> <H2> Http Receiver Servlet active!</h2> <H2> Product version is: 24ai </H2> <H2> Product release version is: 24.1.0.0.0 </H2> <H2> Core release version is: 24.1.0.0.0 </H2> </BODY></HTML> * Connection #0 to host myserver.com left intact thank you very much!

Question We're evaluating different approaches to implement the Outbox Pattern in Oracle 19c for reliable event publishing in our microservices architecture, but we're concerned about the significant I/O overhead and performance implications. Could you provide guidance on the best practices and alternatives? Current Implementation Options We're Considering 1. Traditional Polling Approach Method: Standard outbox table with application polling using SELECT ... FOR UPDATE SKIP LOCKED Concerns: Constant polling creates unnecessary database load Potential for high latency in event delivery Resource consumption even when no events exist 2. Change Data Capture (CDC) with Debezium Method: Using Debezium to mine Oracle redo logs for outbox table changes Concerns: Additional complexity in deployment and monitoring Dependency on external CDC infrastructure Potential log mining overhead on the database 3. Oracle Advanced Queuing (AQ) with Sharded Queues Method: Leveraging Oracle's native messaging with 19c sharded queue improvements Concerns: Learning curve for development teams familiar with table-based approaches Potential vendor lock-in Queue management complexity Primary Concerns I/O Impact: All approaches seem to significantly increase database I/O: Polling creates constant read operations CDC requires continuous log scanning Queuing systems add their own storage and processing overhead Scalability: As our event volume grows, we're worried about: Database performance degradation Increased storage requirements for outbox/queue tables Network bandwidth consumption Specific Questions Performance Optimization: What Oracle 19c specific features or configurations can minimize the I/O overhead of outbox pattern implementations? Alternative Architectures: Are there Oracle-native alternatives to the traditional outbox pattern that provide similar transactional guarantees with better performance characteristics? Hybrid Approaches: Would a combination approach (e.g., AQ for high-priority events, polling for batch operations) be advisable? Monitoring and Tuning: What specific metrics should we monitor, and what tuning parameters are most critical for outbox pattern performance in Oracle 19c? Resource Planning: How should we size our database resources (I/O capacity, storage, memory) when implementing outbox patterns at scale? Environment Details Oracle Database 19c Enterprise Edition Microservices architecture with moderate to high event volume Requirements for exactly-once delivery semantics Mixed OLTP and event-driven workloads Any insights on Oracle-specific optimizations, alternative patterns, or architectural recommendations would be greatly appreciated.

Hi AskTom Team! According to https://docs.oracle.com/en/database/oracle/oracle-database/19/adfns/schema-object-dependency.html#GUID-B99E885E-900F-4F29-A188-A617A301FDCE : "Whenever a procedure is compiled, its time stamp is recorded in the data dictionary." Is it possible to see this recorded timestamp ? Marcin

Bring the consecutive number(strat_val,end_val) record based on id as one record and add new record if the consecutive number is breaks down https://livesql.oracle.com/next/?compressed_code=H4sIAAAAAAAACo3PwQqCQBCA4fvCvsPcVBjBXTWLboXHCoLOMupCgm2wO%252Fr8oXbo1jKn%252BflgmM4ZYgNM7WiAjeemX3YpYikAAIYeZnLdk5yOVZbgVj2T42amEa6Py6m%252Bf7Ox%252FRrBTq%252FWOCmSoxTbDNYbxzBYfv%252BcmWmcjI8hoggV5gv%252FDwvchcEKVRYmlUZVBtIdqkMY1RlqHUbzEvMqkO6xWN9K0%252Fp2%252FgB1bHIywAEAAA%253D%253D&code_language=PL_SQL&code_format=false <code>create table test_date ( id varchar2(10), start_val NUMBER, end_val number );</code> input data : <code>insert into test_date values( 'a',1,3); insert into test_date values( 'a',4,6); insert into test_date values( 'a',7,10); insert into test_date values( 'a',12,15); insert into test_date values( 'a',16,19); insert into test_date values( 'a',20,22); insert into test_date values( 'a',35,37); insert into test_date values( 'a',38,40);</code> output data: 'a' , 1, 10 'a' , 12, 19 'a' , 35 , 40

Why does DML on a materialized view's master table cause the materialized view staleness to change from FRESH to NEEDS_COMPILE? I would have thought it would have changed to STALE. My understanding about NEEDS_COMPILE is that it is supposed to reflect structural changes (DDL), so I must have some gap in my understanding because I am getting NEEDS_COMPILE when only performing DML (not DDL). <code>SQL>column mview_name format a20 SQL>create table T ( id NUMBER 2 ) 3 / Table created. SQL>insert into T ( id ) values ( 1 ) 2 / 1 row created. SQL>create materialized view T_MV 2 ( id 3 ) 4 as select id 5 from T 6 / Materialized view created. SQL>select mview_name, staleness, compile_state, last_refresh_type from user_mviews where mview_name = 'T_MV' 2 / MVIEW_NAME STALENESS COMPILE_STATE LAST_REF -------------------- ------------------- ------------------- -------- T_MV FRESH VALID COMPLETE SQL>select * from T_MV order by id 2 / ID ----------- 1 SQL>insert into T ( id ) values ( 2 ) 2 / 1 row created. SQL>commit 2 / Commit complete. SQL>select mview_name, staleness, compile_state, last_refresh_type from user_mviews where mview_name = 'T_MV' 2 / MVIEW_NAME STALENESS COMPILE_STATE LAST_REF -------------------- ------------------- ------------------- -------- T_MV NEEDS_COMPILE NEEDS_COMPILE COMPLETE SQL>select * from T_MV order by id 2 / ID ----------- 1 SQL>begin 2 dbms_snapshot.refresh( list => user || '.T_MV' 3 , purge_option => 2 4 , atomic_refresh => false 5 , out_of_place => true 6 ) 7 ; 8 end; 9 / PL/SQL procedure successfully completed. SQL>select mview_name, staleness, compile_state, last_refresh_type from user_mviews where mview_name = 'T_MV' 2 / MVIEW_NAME STALENESS COMPILE_STATE LAST_REF -------------------- ------------------- ------------------- -------- T_MV FRESH VALID COMPLETE SQL>select * from T_MV order by id 2 / ID ----------- 1 2 SQL>insert into T ( id ) values ( 3 ) 2 / 1 row created. SQL>commit 2 / Commit complete. SQL>select mview_name, staleness, compile_state, last_refresh_type from user_mviews where mview_name = 'T_MV' 2 / MVIEW_NAME STALENESS COMPILE_STATE LAST_REF -------------------- ------------------- ------------------- -------- T_MV NEEDS_COMPILE NEEDS_COMPILE ...

It appears USING TRUSTED CONSTRAINTS causes a materialized view to have staleness=UNKNOWN when it would otherwise be FRESH. Is it possible to have a materialized view with staleness=FRESH when USING TRUSTED CONSTRAINTS? If not, would the optimizer be less likely to consider a materialized view with staleness=UNKNOWN for query rewrite if query_rewrite_integrity=TRUSTED and query_rewrite_enabled=TRUE? How about if query_rewrite_integrity=ENFORCED? <code>SQL>column mview_name format a20 SQL>create table T ( id NUMBER 2 ) 3 / Table created. SQL>insert into T ( id ) values ( 1 ) 2 / 1 row created. SQL>create materialized view T_MV 2 ( id 3 ) 4 -- refresh using trusted constraints 5 as select id 6 from T 7 / Materialized view created. SQL>create materialized view T_trusted_MV 2 ( id 3 ) 4 refresh using trusted constraints 5 as select id 6 from T 7 / Materialized view created. SQL> SQL>select mview_name, staleness, compile_state, last_refresh_type from user_mviews where mview_name like 'T\_%MV' escape '\' order by 1 2 / MVIEW_NAME STALENESS COMPILE_STATE LAST_REF -------------------- ------------------- ------------------- -------- T_MV FRESH VALID COMPLETE T_TRUSTED_MV UNKNOWN VALID COMPLETE SQL>begin 2 dbms_snapshot.refresh( list => user || '.T_MV' 3 , purge_option => 2 4 , atomic_refresh => false 5 , out_of_place => true 6 ) 7 ; 8 dbms_snapshot.refresh( list => user || '.T_TRUSTED_MV' 9 , purge_option => 2 10 , atomic_refresh => false 11 , out_of_place => true 12 ) 13 ; 14 end; 15 / PL/SQL procedure successfully completed. SQL>select mview_name, staleness, compile_state, last_refresh_type from user_mviews where mview_name like 'T\_%MV' escape '\' order by 1 2 / MVIEW_NAME STALENESS COMPILE_STATE LAST_REF -------------------- ------------------- ------------------- -------- T_MV FRESH VALID COMPLETE T_TRUSTED_MV UNKNOWN VALID COMPLETE SQL>select * from T_MV order by id 2 / ID ----------- 1 SQL>select * from T_trusted_MV order by id 2 / ID ----------- 1 SQL>drop materialized view T_MV 2 / Materialized ...

Hi Tom. Is it possible to return rows from a table in the order that they were inserted? I have an old query, pre 8.1.6, that always returned rows in the order they were inserted. Now, in version 8.1.7 & 9 they are returned in a seemingly random order. Thanks

Hi tom, I have a table with compression, also have partitions and subpartitions. You can see The create DDL on the below. As you can see all of my objects are compressed or nocompressed. Bu i can't see this information on the all_tables table. Compression ad compress_for is turning null. Why i can see the table is compressed on the DDL. What is the point on this issue. <code>CREATE TABLE EFSSALES1 ( sale_id NUMBER, sale_date DATE, region VARCHAR2(10), amount NUMBER ) COMPRESS BASIC PARTITION BY RANGE (sale_date) SUBPARTITION BY HASH (region) ( PARTITION sales_2024 VALUES LESS THAN (TO_DATE('01-JAN-2025','DD-MON-YYYY')) ( SUBPARTITION sp_east1 COMPRESS FOR OLTP, SUBPARTITION sp_west1 NOCOMPRESS ), PARTITION sales_2025 VALUES LESS THAN (TO_DATE('01-JAN-2026','DD-MON-YYYY')) ( SUBPARTITION sp_east2 COMPRESS FOR OLTP, SUBPARTITION sp_west2 COMPRESS FOR OLTP ) ); SELECT compression, COMPRESS_FOR FROM all_tables WHERE table_name = 'EFSSALES1' AND owner='COPYCATLIVE'</code>

Hello Tom, I am wondering what is the benefit of using a recovery catalog over a control file? What are some of the decisions one should consider before going either way? Please and thank you

I am using Windows 11 64 bit / Oracle 19c .Everything works fine except when I create a nested table and associate it with my table as a column . I can neither query it nor drop the table . When I query I get a message that the connection to the database was reset and when I try to drop it I get a message as: RA-00600: internal error code, arguments: [kkpo_rcinfo_defstg:objnotfound], [78561], [], [], [], [], [], [], [], [], [], [] 00600. 00000 - "internal error code, arguments: [%s], [%s], [%s], [%s], [%s], [%s], [%s], [%s], [%s], [%s], [%s], [%s]" *Cause: This is the generic internal error number for Oracle program exceptions. It indicates that a process has encountered a low-level, unexpected condition. The first argument is the internal message number. This argument and the database version number are critical in identifying the root cause and the potential impact to your system. How do I resolve this?