Regarding secondary index

how and when we create secondary indexes and what are the advantages and disadvantages of secondary indexes?

Hi
Index: Technical key of a database table.
Primary index: The primary index contains the key fields of the table and a pointer to the non-key fields of the table. The primary index is created automatically when the table is created in the database.
Secondary index: Additional indexes could be created considering the most frequently accessed dimensions of the table.
Structure of an Index
An index can be used to speed up the selection of data records from a table.
An index can be considered to be a copy of a database table reduced to certain fields. The data is stored in sorted form in this copy. This sorting permits fast access to the records of the table (for example using a binary search). Not all of the fields of the table are contained in the index. The index also contains a pointer from the index entry to the corresponding table entry to permit all the field contents to be read.
When creating indexes, please note that:
An index can only be used up to the last specified field in the selection! The fields which are specified in the WHERE clause for a large number of selections should be in the first position.
Only those fields whose values significantly restrict the amount of data are meaningful in an index.
When you change a data record of a table, you must adjust the index sorting. Tables whose contents are frequently changed therefore should not have too many indexes.
Make sure that the indexes on a table are as disjunctive as possible.
(That is they should contain as few fields in common as possible. If two indexes on a table have a large number of common fields, this could make it more difficult for the optimizer to choose the most selective index.)
Accessing tables using Indexes
The database optimizer decides which index on the table should be used by the database to access data records.
You must distinguish between the primary index and secondary indexes of a table. The primary index contains the key fields of the table. The primary index is automatically created in the database when the table is activated. If a large table is frequently accessed such that it is not possible to apply primary index sorting, you should create secondary indexes for the table.
The indexes on a table have a three-character index ID. '0' is reserved for the primary index. Customers can create their own indexes on SAP tables; their IDs must begin with Y or Z.
If the index fields have key function, i.e. they already uniquely identify each record of the table, an index can be called a unique index. This ensures that there are no duplicate index fields in the database.
When you define a secondary index in the ABAP Dictionary, you can specify whether it should be created on the database when it is activated. Some indexes only result in a gain in performance for certain database systems. You can therefore specify a list of database systems when you define an index. The index is then only created on the specified database systems when activated
Regards

Similar Messages

Regarding Secondary Index in a Table

hi
if i create a secondary index in a table is it obligatory or optional to have first field as MANDT (Client field) if the table is client dependent & how many secondary indexes(MAXIMUM) can be created for a table.
Regards

Hi,
Check the below Link
How to transport a secondary index on P master data table?
Hope this helps you.
Regards,
Anki Reddy

Creation of secondary indexes due to heavy flow of messages in ecc smq2

Hi gurus,
So we are facing smq2 issues from last 15 days in Ecc system due to some Time Limit Exceed and some times Object is Locked by the user xxxx
So finally we decided to go for creating seconday indexes in Ecc side , So here my question is there any thing required from Pi side while creating
Secondary indexes why i am asking this question is there is no issues From PI end after reaching to target(ECC) system only messages got stucking
in smq2 and facing issues .Below is the interface details.
ECC-FSCM
SAP ECC 6.0
FSCM
CreditCommitment_In and CreditCommitment_Out
CC_ProxySender_FSCM
CC_ProxyReceiver_FSCM
Plz reply back .
Regards
Madhu

If you had gone through the replies in your previous post, Iñaki Vilaand myself already provided the report name which needs to be scheduled to clear the messages in queues.
Plz provide the permanent fix for this issue

Regarding LOB index

Hi,
I am having a SQL loader mapping where in I am loading data from a CSV file to Oracle target table.
My target table is having a CLOB column. Now, due to this a LOB index has also been created for this column.
My CSV is having 1 million records and when I execute the mapping it gets hang and doesnot load anything.
I think that due to that LOB index the execution is taking so long. Is there any way that I can disable this index during run-time. I tried but it gave me error: ORA-22864: cannot ALTER or DROP LOB indexes.
Can anyone of you suggest any alternate to this.
Thanks!!!!

Hey Fren,
We have Secondary index to shorten the search time and thus to increase the proficiency in selecting the accurate records from numerous fields available for the option...
That means, we can say that Secondary Index can act as an Extension to the Primary Key fields available to Shorten the Search time.....
But if you use 'OR' condition and give a SELECT Query in your report it will act as the reverse effect of Secondary index......
Instead you can create the Secondary Index including the key fields with some extension to the same...
Means For example,
Table 1:
Field1 [x] CHAR 10
Field2 [x] CHAR 10
Field3 [ ] NUMC 10
Field4 [ ] CHAR 10
Field5 [ ] CHAR 10
Field6 [ ] NUMC 10
Field7 [ ] CHAR 10
Field8 [ ] CHAR 10
Field9 [ ] NUMC 10
Field10 [ ] CHAR 10
Field11 [ ] CHAR 10
Field12 [ ] NUMC 10
Field13 [ ] CHAR 10
Field14 [ ] CHAR 10
Field15 [ ] NUMC 10
Field16 [ ] CHAR 10
Field17 [ ] CHAR 10
Field18 [ ] NUMC 10
Field19 [ ] CHAR 10
Field20 [ ] CHAR 10
Field21 [ ] NUMC 10
Field22 [ ] CHAR 10
Field23 [ ] CHAR 10
Field24 [ ] NUMC 10
So you can have Field 3 Field4 Field5 Field6 as your secondary index.....
Thats it,
Thank you,
Inspire If Needful,
Warm Regards,
Abhi

What is the "No database index" means when you Creating Secondary Indexes?

HI,
   I'm Creating Secondary Indexes in the maintenance screen of the table(se11)
   There are three options under "Non-unique Index":
   1.Index on all database systems
   2.For selected database systems
   3.No database index
My questions is :
What do u mean by "No Database Index" and when is it used.
Can anybody plz tell me what's the difference of this three options ?
Here is what i found in the help:
   No database index: The index is not created in the database. If you
   choose this option for an index that already exists in the database,
   it is deleted when you activate this option.

Hi,
It is clear from the help documentation,
Here see what the help document says:
Create the index in the database (selection)
Whether an index improves or worsens performance often depends on the database system. You can therefore set whether an index defined in the ABAP Dictionary should be created in the database.
This makes it easier to install a platform-specific customer system.
You can set this option as follows:
1. Index in all database systems: The index is always created in the database.
2. In selected database systems: The index is created depending on the database system used. In this option, you must specify the databases in which the indexes are to be created. You can do this either on an inclusive (list of systems on which it should be created) or an exclusinve (list of systems on which it should not be created) basis. In either case, you can list up to four different database systems.
3. No database index:: The index is not created in the database. If you set this option for an index that already exists in the database, it is deleted when you activate the table in the ABAP Dictionary.
Note: Unique indexes have an extra function, and must therefore always be created in the database. The database system prevents entries or index fields being duplicated. Since programs may rely on this database function, you cannot delete unique indexes from the database.
Hope it helps you,
Regards,
Abhijit G. Borkar

Secondary Index Select Statement Problem

Hi friends.
I have a issue with a select statement using secondary index,
SELECT SINGLE * FROM VEKP WHERE VEGR4 EQ STAGE_DOCK
                                  AND VEGR5 NE SPACE
                                  AND WERKS EQ PLANT
        %_HINTS ORACLE
        'INDEX("&TABLE&" "VEKP~Z3" "VEKP^Z3" "VEKP_____Z3")'.
given above statement is taking long time for processing.
when i check for the same secondary index in vekp table i couldn't see any DB index name with vekp~z3 or vekp^z3 or vekp____z3.
And the sy-subrc value after select statement is 4. (even though values avaliable in VEKP with given where condition values)
My question is why my select statement is taking long time and sy-subrc is 4?
what happens if a secnodary index given in select statement, which is not avaliable in that DB Table?

Hi,
> ONe more question: is it possible to give more than one index name in select statement.
yes you can:
read the documentation:
http://download.oracle.com/docs/cd/A97630_01/server.920/a96533/hintsref.htm#5156
index_hint:
This hint can optionally specify one or more indexes:
- If this hint specifies a single available index, then the optimizer performs
a scan on this index. The optimizer does not consider a full table scan or
a scan on another index on the table.
- If this hint specifies a list of available indexes, then the optimizer
considers the cost of a scan on each index in the list and then performs
the index scan with the lowest cost. The optimizer can also choose to
scan multiple indexes from this list and merge the results, if such an
access path has the lowest cost. The optimizer does not consider a full
table scan or a scan on an index not listed in the hint.
- If this hint specifies no indexes, then the optimizer considers the
cost of a scan on each available index on the table and then performs
the index scan with the lowest cost. The optimizer can also choose to
scan multiple indexes and merge the results, if such an access path
has the lowest cost. The optimizer does not consider a full table scan.
Kind regards,
Hermann

DSO activation problem after creating the secondary indexes

Hi,
I am facing the problem with DSO activation after creating the secondary indexes.
Compared with Info Cubes there is no functionality available which allows dropping and recreating a secondary index before/after the data activation.
As a workaround I can write a simple report which drops and creates the indexes on database level.
By using a process chain, we can simply insert the drop index report before data activation and the create index report after the data activation process.
Can any body help me step by step procedure or Material to write the programs for delete index and create index reports on DSO object?..
Thanks in advance for your help.
Thanks & Regards,
Bala

hi,
in BI if you are using the dso for reporting then you can simply chk the settings of dso for SID generation.
no need to create the indexes or delete it.
if the dso is not used for report then no need to use indexes.
Ramesh

Database tableAUFM hitting is taking much time even secondary index created

Hi Friends,
 There is report for Goods movement rel. to Service orders + Acc.indicator.
 We have two testing Systems(EBQ for developer and PEQ from client side).
 EBQ system contains replica of PEQ every month.
 This report is not taking much time in EBQ.But it is taking much time in PEQ.For the selection criteria I have given,both systems have same data(Getting same output).
The report has the follwoing fields on the selection criteria:
A_MJAHR Material Doc. Year (Mandatory)
S_BLDAT Document Date(Optional)
S_BUDAT Posting Date(Optional)
S_LGORT Storage Location(Optional)
S_MATNR Material(Optional)
S_MBLNR Material Documen(Optional)t
S_WERKS Plant(Optional)
Client not agrrying to make Material Documen as Mandatory.
The main (first) table hit is on AUFM table .As there are non-key fileds as well in where condition,We have cretaed a secondary index as well for AUFM table on the following fields:
BLDAT
BUDAT
MATNR
WERKS
LGORT
Even then also ,in PEQ sytem the report is taking very long time ,Some times not even getting the ALV output.
What can be done to get teh report executed very fast.
<removed by moderator>
The part of report Soure code is as below:
<long code part removed by moderator>
Thanks and Regards,
Rama chary.P
Moderator message: please stay within the 2500 character limit to preserve formatting, only post relevant portions of the code, also please read the following sticky thread before posting.
Please Read before Posting in the Performance and Tuning Forum
locked by: Thomas Zloch on Sep 15, 2010 11:40 AM

Hi Friends,
 There is report for Goods movement rel. to Service orders + Acc.indicator.
 We have two testing Systems(EBQ for developer and PEQ from client side).
 EBQ system contains replica of PEQ every month.
 This report is not taking much time in EBQ.But it is taking much time in PEQ.For the selection criteria I have given,both systems have same data(Getting same output).
The report has the follwoing fields on the selection criteria:
A_MJAHR Material Doc. Year (Mandatory)
S_BLDAT Document Date(Optional)
S_BUDAT Posting Date(Optional)
S_LGORT Storage Location(Optional)
S_MATNR Material(Optional)
S_MBLNR Material Documen(Optional)t
S_WERKS Plant(Optional)
Client not agrrying to make Material Documen as Mandatory.
The main (first) table hit is on AUFM table .As there are non-key fileds as well in where condition,We have cretaed a secondary index as well for AUFM table on the following fields:
BLDAT
BUDAT
MATNR
WERKS
LGORT
Even then also ,in PEQ sytem the report is taking very long time ,Some times not even getting the ALV output.
What can be done to get teh report executed very fast.
<removed by moderator>
The part of report Soure code is as below:
<long code part removed by moderator>
Thanks and Regards,
Rama chary.P
Moderator message: please stay within the 2500 character limit to preserve formatting, only post relevant portions of the code, also please read the following sticky thread before posting.
Please Read before Posting in the Performance and Tuning Forum
locked by: Thomas Zloch on Sep 15, 2010 11:40 AM

Is it worth creating secondary index on BKPF table ?

Hello,
One of my clients is using ECC version 5.0. I have a requirement wherein I need to fetch the data from BKPF table based on AWKEY, BUKRS and GJAHR. There is no standard secondary index available.
I have decided to create a secondary index on these fields in the following order:
1) MANDT
2) AWKEY
3) BUKRS
4) GJAHR
I know that creating secondary indexes does improve performance during data retrieval. But when I checked the total number of entries in BKPF table in production system, there are more than 20 lac 2 million records.
I am worried that creation of secondary index will create another table of such a large size in production that has data sorted on the above fields. Also, the RAM of production system is 6 GB.
Please suggest if creation of secondary index is a good measure OR should I recommend the client to increase the system RAM?
Regards,
Danish.
Edited by: Thomas Zloch on Oct 3, 2011 3:01 PM

Hi,
Secondary Index on BKPF-AWKEY has been successfully created in production. The report which used to timeout in foreground as well as in background is now executing in less than 10 seconds !!
Client is very much satisfied with this. But, there is one problem that we are facing now is that when the user is changing an existing billing document via VF02, on SAVE, system takes a very long time to save the changes done.
We monitored the processes via SM50 and found that there was a sequential read on BKPF table.
Before transporting the index in production, system approximately took not more than 5 seconds to save the Billing Document. But now system takes more than 20 minutes just to save the billing document via VF02.
I really don't know what has gone wrong. I can't figure out if I have missed any step while creating the index.
I did the following,
1) Created a Secondary index on BKPF, saved it in the transport request and activated it. Since the index was not existing in database ORACLE, I activated and adjusted the table via SE14. Now, index exists on database as well. Working perfectly in development.
2) Imported the transport request to Production. Checked in SE11. Index was existing and active. Also, index existed in database ORACLE.
Have I missed anything ? Is it required to activate and adjust the database via SE14 in production too ?
Regards,
Danish.

Creation of Secondary Index

Hi...
Scenario:
I have loaded BX and BF as per practice. However, i am not getting current stock values for materials which had 0 opening stock when BX was pulled (I did not select checkbox 'Zero stock to be transferred'). Note 823951 suggests executing program 'SAP_REFPOINT_COMPLETE' in such scenario.
Probelm:
The note suggests creating an index on all dimensions except time. However, the E table for 0IC_C03 is in local package both on development and production system. Hence, am unable to create and transport the index. How do we create secondary index on InfoCube?
Also, when the program is executed in check mode (without creating the suggested index) it ran for almost 7 hrs without any result. Does this program take huge time to complete even in check mode?
Thanks & Regards,
Anoop Sahu

Hi,
You can create index from Data Dictionary also.
Goto se11-> choose table radio button -> give your table name -> click on change
this will shows the table fields screen.
In that screen select Create Index button -> Choose the required field.
Every table should maintain a primary index when table was created based on the primary key of that table. if we create new index then it is called secondary index.
usng above procedure u can create secondary index. Just try
Regards,
BRS

Buffering and creation of secondary indexes.

Hi All,
I have a table that has more than 6 million records, due to which performance is slow during the transaction search, kindly let me know if Buffering and creation of secondary indexes will help me.
I am given to understand that creation of seconary indexes and full buffering may not always improve performance. Kindly let me know when it is advised to go for full buffering.
Regards,
Thiru

Hi,
create secondary index for the table
check below link
http://help.sap.com/saphelp_nw70/helpdata/en/cf/21eb20446011d189700000e8322d00/content.htm
Regards,
Madhu

SELECT QUERY BASED ON SECONDARY INDEX

Hi all,
CAN ANYONE TELL ME HOW TO WRITE SELECT QUERY BASED ON SECONDARY INDEX.
IN WHAT WAY DOES IT IMPROVE PERFORMANCE.
i KNOW WHEN CREATING SECONDARY INDEX I NEED TO GIVE AN INDEX NO -iT SHOULD BE ANY NUMBER RIGHT?
I HAVE TO LIST ALL PRIMARY KEYS FIRST AND THEN THE FIELD FOR WHICH I AM CREATING SECONDARY INDEX RIGHT?
LETS SAY I HAVE 2 PRIMARY KEYS AND I WANT TO CREATE SEONDARY INDEX FOR 2 FIELDS THEN
I NEED TO CREATE A SEPERTE SECONDARY INDEX FOR EACH ONE OF THOSE FIELDS OR ONE SHOULD BE ENOUGH
pLS LET ME KNOW IF IAM WRONG

HI,
If you cannot use the primary index to determine the result set because, for example, none of the primary index fields occur in the WHERE or HAVINGclauses, the system searches through the entire table (full table scan). For this case, you can create secondary indexes, which can restrict the number of table entries searched to form the result set.
You create secondary indexes using the ABAP Dictionary. There you can create its columns and define it as UNIQUE. However, you should not create secondary indexes to cover all possible combinations of fields.
Only create one if you select data by fields that are not contained in another index, and the performance is very poor. Furthermore, you should only create secondary indexes for database tables from which you mainly read, since indexes have to be updated each time the database table is changed. As a rule, secondary indexes should not contain more than four fields, and you should not have more than five indexes for a single database table.
What to Keep in Mind for Secondary Indexes:
http://help.sap.com/saphelp_nw04s/helpdata/en/cf/21eb2d446011d189700000e8322d00/content.htm
http://www.sap-img.com/abap/quick-note-on-design-of-secondary-database-indexes-and-logical-databases.htm
Regards
Sudheer

Select query with secondary index

hi,
i have a report which is giving performance issues on a perticular select query on KONH table.
the select query doesnt use the primary key fields and table already has around 19 million entries.So there was a secondary index created for the fields in the table.
now, KONH is a client specific table, and hence has MANDT as the first field. when the table is not indexed it is sorted according to the order of fields, like first MANDT, then primary key fields and then remaining fields.. (correct me if i am wrong)
but the secondary index created doesnt has MANDT in it..(yea, a mistake! )...
but instead of correccting the secondary index, i am told to change the select query..
so, i used a "client specific" syntax to sort the issue.. but i dont understand whre i should put the "where mandt eq sy-mandt" clause..
should i put it right after all my secondary index fields are over? or what happens to the order of fields which are not present in the list of secondary index?
kindaly help.
thanx.

Hi chinmay kulkarni,
its better if you can ask concerned person to add MANDT field in your index as well....
Indexes and MANDT
If a table begins with the mandt field, so should its indexes. If a table begins with mandt and an index doesn't, the optimizer might not use the index.
Remember, if you will, Open SQL's automatic client handling feature. When select * from ztxlfa1 where land1 = 'US' is executed, the actual SQL sent to the database is select * from ztxlfa1 where mandt = sy-mandt and land1 = 'US'. Sy-mandt contains the current logon client. When you select rows from a table using Open SQL, the system automatically adds sy-mandt to the where clause, which causes only those rows pertaining to the current logon client to be found.
When you create an index on a table containing mandt, therefore, you should also include mandt in the index. It should come first in the index, because it will always appear first in the generated SQL.
Index: Technical key of a database table.
Primary index: The primary index contains the key fields of the table and a pointer to the non-key fields of the table. The primary index is created automatically when the table is created in the database.
Secondary index: Additional indexes could be created considering the most frequently accessed dimensions of the table.
Structure of an Index
An index can be used to speed up the selection of data records from a table.
An index can be considered to be a copy of a database table reduced to certain fields. The data is stored in sorted form in this copy. This sorting permits fast access to the records of the table (for example using a binary search). Not all of the fields of the table are contained in the index. The index also contains a pointer from the index entry to the corresponding table entry to permit all the field contents to be read.
When creating indexes, please note that:
An index can only be used up to the last specified field in the selection! The fields which are specified in the WHERE clause for a large number of selections should be in the first position.
Only those fields whose values significantly restrict the amount of data are meaningful in an index.
When you change a data record of a table, you must adjust the index sorting. Tables whose contents are frequently changed therefore should not have too many indexes.
Make sure that the indexes on a table are as disjunctive as possible.
(That is they should contain as few fields in common as possible. If two indexes on a table have a large number of common fields, this could make it more difficult for the optimizer to choose the most selective index.)
For Example...
SELECT KUNNR KUNN2 INTO TABLE T_CUST_TERR
FROM KNVP CLIENT SPECIFIED
WHERE MANDT = SY-MANDT " here MANDT shd be first
AND KUNN2 IN S_TERR
AND PARVW LIKE 'Z%'.
Accessing tables using Indexes
The database optimizer decides which index on the table should be used by the database to access data records.
You must distinguish between the primary index and secondary indexes of a table. The primary index contains the key fields of the table. The primary index is automatically created in the database when the table is activated. If a large table is frequently accessed such that it is not possible to apply primary index sorting, you should create secondary indexes for the table.
The indexes on a table have a three-character index ID. '0' is reserved for the primary index. Customers can create their own indexes on SAP tables; their IDs must begin with Y or Z.
If the index fields have key function, i.e. they already uniquely identify each record of the table, an index can be called a unique index. This ensures that there are no duplicate index fields in the database.
When you define a secondary index in the ABAP Dictionary, you can specify whether it should be created on the database when it is activated. Some indexes only result in a gain in performance for certain database systems. You can therefore specify a list of database systems when you define an index. The index is then only created on the specified database systems when activated
Also pls have a look on below link
http://www.sapfans.com/sapfans/forum/devel/messages/30240.html
Hope it will solve your problem..
Reward points if useful...
Thanks & Regards
ilesh 24x7

Secondary Index Picked with one field short in select query

Hi,
We have a select query as follows
select single lgort       vgbel        vgpos
    into   (lips-lgort,lips-vgbel,lips-vgpos)
    from    lips
   where         vbeln          Eq p_zlcpp-vbeln
     and         matnr          Eq p_zlcpp-matnr
     and         charg          Eq p_zlcpp-charg
The secondary index ZB has the fields as follows:
MANDT     Client
MATNR     Material Number
CHARG     Batch Number
BWART     Movement Type (Inventory Management)
When seen in the trace it seems the select query picks this secondary index. Whether it is correct? since i find no BWART in the select query. Because of this index the query take large time. I used the Hint statement as follows:
select single lgort       vgbel        vgpos
    into   (lips-lgort,lips-vgbel,lips-vgpos)
    from    lips
   where         vbeln          Eq p_zlcpp-vbeln
     and         matnr          Eq p_zlcpp-matnr
     and         charg          Eq p_zlcpp-charg   %_HINTS ORACLE 'INDEX("LIPS" "LIPS~0")' .
and it now works fast. Please advice the best way to make the select query work on itself without using the hint statement to pick the index LIPS~0 instead of the invalid secondary index ZB.
Thanks & Regards,
Selvakumar M.
Edited by: Selva on Jun 17, 2011 7:35 PM

Hello Selva,
your problem here is the decision of the optimizer that does not exactly know the selectivity of the fields.
If your deliveries are normally small (not too many items), then selecting via the document number will be relatively fast.
And selecting via the material number + batch will be slow in case if many deliveries are having same product from the same batch delivered.
I assume that the latest is the case in your system. That's why the selection with ZB index is slow.
If the data distribution is as I described above, then your hint is quite OK and I advise you to stick to the hint.
From my PoV this is the better solution rather changing the coding and throwing out MATNR field from the WHERE clause to filter later in ABAP.
Another solution would be trying to play with histograms. But you'll need %SUBSTITUTE VALUES% or %SUBSTITUTE LITERALS% hint anyway, so I find your solution better.
So, please stay with hint. Even SAP standard development does it for some select statements.
Regards,
Yuri

Strange problem while building a secondary index.

Hi,
I have a strange problem in creating a secondary index which is a part of primary data.
I tested my program and a working sample program
My data scheme looks like:
   Key = unique string
   Data = structure {
                    time_t timestamp;
    Secondary Key = timestamp in data (NOT unique)
My BDB environment flags is "DB_CREATE | DB_INIT_CDB | DB_INIT_MPOOL | DB_THREAD"
The primary DB is created as BTREE with a custom key compare function provided by calling DB->set_bt_compare.
int my_key_compare(DB *db, const DBT *key1, const DBT *key2)
     const char *k1_v = (const char *)key1->data;
     const char *k2_v = (const char *)key2->data;
     return strcmp(k1_v, k2_v);
The secondary Index DB is created as BTREE while permitting duplication. (DB_DUPSORT)
It has two custom callback functions; one for data compare, the other for extracting a data from the primary data.
int my_extract_timestamp(DB *db, const DBT *primary_key, const DBT *primary_data, DBT *secdondary_key)
     secondary_key->data = ( (MY_DATA *)(primary_data->data))->timestamp;
     secondary_key->size = sizeof(time_t);
     return 0;
int my_secondary_dup_compare(DB *db, const DBT *key1, const DBT *key2)
     time_t      k1_v = *(time_t *)key1->data;
     time_t      k2_v = *(time_t *)key2->data;
     return k1_v - k2_v;
The function 'my_extract_timestamp' is set by calling DB->associate().
My problem is 'my_secondary_dup_compare' function called with a strange DBT values.
I think the values should point to the value provided from my_extract_timestamp(), but they pointed to
the key which provided when calling DB->put on the primary DB.
Could somebody help me ?
Any help highly appreciated.

Hi,
In the secondary database, the key is what you extract and the data is the key of the primary database. As your primary key is a unique string, your data in secondary database is also a unique string. The DB->set_dup_compare sets the comparison function for the duplicate data, so you are comparing time stamps on unique strings, not on what you extract.
As you are comparing the time stamps which are the keys of secondary database, I guess here you want to set the bt_compare function instead of the dup_compare for the secondary database.
Also, about this sentence:
secondary_key->data = ( (MY_DATA *)(primary_data->data))->timestamp;
The DBT.data should be an address, but this is a value here instead of an address.
Regards,
Winter, Oracle Berkeley DB

Regarding secondary index

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