Opened 10 years ago

Closed 10 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)

ticket1996.patch (4.2 KB ) - added by zhanga 10 years ago.
DE22116.patch (2.1 KB ) - added by christinebao 7 years ago.

Download all attachments as: .zip

Change History (4)

by zhanga, 10 years ago

Attachment: ticket1996.patch added

comment:1 by zhanga, 10 years ago

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

comment:2 by jng, 10 years ago

Resolution: fixed
Status: newclosed

by christinebao, 7 years ago

Attachment: DE22116.patch added
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