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Hi all,</div>
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MY MAPFILE: <a href="https://pastebin.com/6A98L6V7">https://pastebin.com/6A98L6V7</a></div>
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I am running into an issue with WMS GetFeatureInfo when using FlatGeobuf (FGB) as a TILEINDEX source in MapServer. The problem appears to be related to how MapServer / OGR handles multiple records inside a FlatGeobuf tile index.</div>
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<br>
</div>
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Environment:</div>
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- MapServer: 8.6.0-beta2</div>
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- GDAL: 3.12.0</div>
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- PROJ: 9.7.0</div>
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- OS: Debian Bookworm (Docker)</div>
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<br>
</div>
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TileIndex structure:</div>
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I am using FlatGeobuf as a tile index, with a schema similar to a classic shapefile tile index.</div>
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The TILEITEM column is called "location" and contains both the file path and the layer name,</div>
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separated by a comma:</div>
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</div>
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location</div>
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data/CLMS_UA_LCU_S2021_V025ha_BA001L1_SARAJEVO_03035_V01_R01_20250523.fgb,CLMS_UA_LCU_S2021_V025ha_BA001L1_SARAJEVO_03035_V01_R01_20250523</div>
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data/CLMS_UA_LCU_S2021_V025ha_AT001L3_WIEN_03035_V01_R01_20250418.fgb,CLMS_UA_LCU_S2021_V025ha_AT001L3_WIEN_03035_V01_R01_20250418</div>
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Each referenced FlatGeobuf file contains exactly one vector layer, and the layer name matches</div>
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the name provided after the comma in the tile index.</div>
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Problem description:</div>
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- I have vector layers configured in MapServer using CONNECTIONTYPE OGR with TILEINDEX pointing to an FGB file.</div>
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- The layers are only visible at large scales (MAXSCALEDENOM 300000), where vector data is queried.</div>
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- When issuing a WMS GetFeatureInfo request at an appropriate zoom level:</div>
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- GetFeatureInfo works correctly for features coming from the FIRST record in the tile index.</div>
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- Features coming from any subsequent tile index record never return GetFeatureInfo results.</div>
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- The request itself is valid (correct bbox, x/y, tolerance, scale), and rendering works correctly</div>
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for all tiles — only GetFeatureInfo is affected.</div>
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</div>
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Additional observations:</div>
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- Reordering records inside the FlatGeobuf tile index changes which dataset GetFeatureInfo works for.</div>
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Whichever record is first starts working; the others stop working.</div>
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- If I bypass the tile index and connect directly to a single FlatGeobuf file using:</div>
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CONNECTION "path/to/file.fgb"</div>
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DATA "layer_name"</div>
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then GetFeatureInfo works as expected.</div>
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- To further isolate the issue, I created a separate MapServer layer only for the Vienna dataset</div>
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(the dataset affected by the problem), with an explicit CONNECTION and DATA pointing directly</div>
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to the FlatGeobuf file and its internal layer name (no TILEINDEX involved).</div>
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- In this setup, with the layer name explicitly defined, GetFeatureInfo works correctly and</div>
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consistently for Vienna features.</div>
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- This strongly suggests that the problem is not related to the data itself, styles, templates,</div>
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or scale settings, but specifically to the use of FlatGeobuf as a TILEINDEX source during</div>
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GetFeatureInfo processing.</div>
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- It appears that during GetFeatureInfo MapServer / OGR only evaluates the first tile index</div>
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record and does not properly iterate over or reset OGR datasets for subsequent records,</div>
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especially when different internal layer names are involved.</div>
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My suspicion is that this may be a limitation or bug in how FlatGeobuf is handled as a TILEINDEX</div>
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source, particularly for GetFeatureInfo requests.</div>
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Has anyone encountered similar behaviour when using FlatGeobuf tile indexes with GetFeatureInfo,</div>
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or can confirm whether this is a known limitation in MapServer or GDAL/OGR?</div>
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Thanks,</div>
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Marcin</div>
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