Notice: this Wiki will be going read only early in 2024 and edits will no longer be possible. Please see: https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/wikis/Wiki-shutdown-plan for the plan.
Difference between revisions of "MemoryAnalyzer/OQL"
(→Object Query Language) |
|||
| Line 41: | Line 41: | ||
''[I@620f7a39'' is a regular Java integer array holding a several of ints which are the object IDs Memory Analyzer uses | ''[I@620f7a39'' is a regular Java integer array holding a several of ints which are the object IDs Memory Analyzer uses | ||
to represent IObjects in the snapshot. | to represent IObjects in the snapshot. | ||
| + | |||
| + | |||
| + | == OQL (Memory Analyzer) versus SQL (MAT/Calcite) == | ||
| + | |||
| + | As well as the built-in OQL, there is an extension plug-in for MAT called MAT Calcite which adds SQL processing | ||
| + | |||
| + | {| | ||
| + | |- | ||
| + | !Topic | ||
| + | !OQL | ||
| + | !SQL | ||
| + | |- | ||
| + | |General syntax | ||
| + | |SELECT s FROM java.lang.String | ||
| + | |SELECT s.this FROM java.lang.String | ||
| + | |- | ||
| + | |} | ||
Revision as of 05:15, 14 November 2019
Object Query Language
Object Query Language is an SQL like language used by Memory Analyzer for exploring a heap dump.
Simple
SELECT * FROM java.lang.String
Displays all String objects as a tree.
SELECT s as String,s.value as "characters" FROM java.lang.String s
Displays all String objects as a table.
SELECT s as String,s.value as "characters", inbounds(s),inbounds(s).@length FROM java.lang.String s
String |characters |inbounds(s)| inbounds(s).@length -------------------------------------------------------------------------------------------------------------- java.lang.String [id=0x22e58820]|char[] [id=0x22e60f50;length=16;size=48] |[I@620f7a39| 1 java.lang.String [id=0x22e59150]|char[] [id=0x22e62ff0;length=6;size=24] |[I@1f7b8d59| 1 java.lang.String [id=0x22e5b560]|char[] [id=0x22e6b730;length=537;size=1088]|[I@28551755| 1 --------------------------------------------------------------------------------------------------------------
There are two sorts of objects encountered with OQL, IObject which represent Java objects in the snapshot and regular Java objects generated by OQL processing.
java.lang.String [id=0x22e58820] is a IInstance representing a String from the snapshot.
char[] [id=0x22e60f50;length=16;size=48] is an IPrimitiveArray representing a character array from the snapshot.
[I@620f7a39 is a regular Java integer array holding a several of ints which are the object IDs Memory Analyzer uses to represent IObjects in the snapshot.
OQL (Memory Analyzer) versus SQL (MAT/Calcite)
As well as the built-in OQL, there is an extension plug-in for MAT called MAT Calcite which adds SQL processing
| Topic | OQL | SQL |
|---|---|---|
| General syntax | SELECT s FROM java.lang.String | SELECT s.this FROM java.lang.String |