About COUNT

manual

GROUP BY and HAVING clauses

Explains how to use the GROUP BY and HAVING clauses in a JPA/JPQL query.... value combination). Aggregate calculations (count, sum, avg, max, min) that are carried out on all the objects (or the ... the five aggregate functions of SQL: COUNT - returns a long value representing the number of elements. ...

 
api-jpa

count(x)

Create an aggregate expression applying the count operation.(Method of javax.persistence.criteria.CriteriaBuilder)

 
issue

Negative snapshot user count

I finally hit an instance of the "Negative snapshot user count" exception 1) ... I finally hit an instance of the "Negative snapshot user count" exception 1) [ObjectDB 2.3.2_01] Unexpected exception ... Negative snapshot user count com.objectdb.o.InternalException: Negative snapshot user count at com.objectdb.o.SNP.z(SNP.java:292) at ...

 
issue

Negative snapshot user count exception

I found the following stack trace in my log files; it's cropped up a number of times: ... Negative snapshot user count com.objectdb.o.InternalException: Negative snapshot user count at com.objectdb.o.SNP.D(SNP.java:344) at ... issues. In that case, the "Negative snapshot user count" and the "mismatch client-server protocol" errors could be caused by a ...

 
manual

Strings in JPQL and Criteria Queries

Explains string expressions in JPQL queries, including LIKE, LOCATE, LOWER, UPPER, TRIM, CONCAT and SUBSTRING. String values may appear in JPQL queries in various forms: as  string literals - e.g. 'abc' , ''. as parameters - when string values are assigned as arguments. as  path e ...

 
forum_thread

Unexpected COUNT Results

We are working with objectDB version 2.5.5.b01. (we also tried to use the latest version 2.6.1) We have several issues with queries that can be seen with the attached database and using ObjectDB explorer: 1.       Using ObjectDB explorer... 1380. This is expected result If we add COUNT operator: b.      SELECT COUNT($1.id) FROM Pa3DataKey $1 WHERE $1.timestamp <= 187526 AND ... e.g: c.       SELECT COUNT($1.id) FROM Pa3DataKey $1 WHERE $1.timestamp <= 187526 AND ...

 
issue

ClassCastException thrown when running count query

Hello! Attached you find a full stacktrace. The query was: ... a full stacktrace. The query was: SELECT COUNT ( t ) FROM Position t WHERE ( ( t. unit = ... produces a null pointer exception. Now back to the count query: SELECT COUNT ( t ) FROM Position t ...

 
forum_thread

Processing thread count for 8-core server

In reference to the information here:  http://www.objectdb.com/java/jpa/setting/database#The_processing_element_   We are working with an 8-core processor.  The recommended thread count is "more than the number of cores but not too many."  What would be an appropriate number of threads for the processing thread pool in order to get good performance for our 8-core server? ... with an 8-core processor.  The recommended thread count is "more than the number of cores but not too many."  What would be ...

 
forum_thread

Threading Problem (maybe with Criteria)

Hi all I found some threading problems I do not understand: here is the the link to the testcase http://www.advolux.de/weblink%20forum/test.zip ... FETCH thread nr ( 36 ) count : 982 UIDs in 26 msek FETCH thread nr ( 41 ) count : 982 UIDs in 29 msek FETCH thread nr ( 44 ) ...

 
api-jpa

countDistinct(x)

Create an aggregate expression applying the count distinct operation.(Method of javax.persistence.criteria.CriteriaBuilder)