Opened 13 years ago
Closed 12 years ago
#1996 closed defect (fixed)
ReadNext method loops when using SqLite database
| Reported by: | zhanga | Owned by: | |
|---|---|---|---|
| Priority: | medium | Milestone: | 2.3 |
| Component: | Feature Service | Version: | 2.1.0 |
| Severity: | trivial | Keywords: | ReadNext Sqlite |
| Cc: | External ID: | 1456425 |
Description
The code below works fine using Oracle Database but it loops using SQLite database. .... MgReader sqlReader = _featureService.ExecuteSqlQuery(_resourceIdentifier, strSQL);
int cpt = 0; while (sqlReader.ReadNext()) { cpt++; } ....
Attachments (2)
Change History (4)
by , 13 years ago
| Attachment: | ticket1996.patch added |
|---|
comment:1 by , 13 years ago
comment:2 by , 12 years ago
| Resolution: | → fixed |
|---|---|
| Status: | new → closed |
by , 10 years ago
| Attachment: | DE22116.patch added |
|---|
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When call ReadNext() in from web-tier side, it actually doesn’t send a ReadNext() operation request to Map Server. Instead, it sends a GetRows operation request to get a lot of records, then cache the records. If the GetRows operation returns an empty collection, then we think we have reached the end of the reader. But there is no specification in the FDO API about what we should do in case an application calls again ReadNext after reader is depleted. In SQLite the sqlite engine resets the statement automatically and start it over again. Therefore, the GetRows method will never return an empty collection for Sqlite database. Then the ReadNext() method in the web app would be an endless loop. This submission fixes ServerDataReader and ServerSqlDataReader to make IM Server runs correctly when using SQLite database.
MG Open Source: Server/src/Services/Feature/ServerDataReader.cpp Server/src/Services/Feature/ServerDataReader.h Server/src/Services/Feature/ServerSqlDataReader.cpp Server/src/Services/Feature/ServerSqlDataReader.h