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Indexing attribute columns in Precisely MapInfo Extended TAB

  • Feb 19, 2026 11:55 PM UTC
  • 4 replies
  • 97 views
nicholas
Contributor
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I am using the Precisely MapInfo Extended TAB Writer to generate a MapInfo table that is over 2GB (total) in file size. I estimate it should be between 3GB and 4GB in size.

I am indexing five attribute columns in the table.

And the process of indexing the attribute columns is extremely slow.

When I do not index any columns, it takes about 20 minutes to Write the table

With indexing the columns, it can run for twelve hours before I halt the process in frustration to check my process.

Does anyone have any experience of this? Is the Precisely MapInfo Extended TAB Writer just bad at generating indexes?

    4 replies

    j.botterill
    Evangelist
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    • j.botterillEvangelist
    • Evangelist
    • Feb 20, 2026 7:34 AM UTC

    Indexes are created incrementally during the write

    Each attribute index is written to the .IND file, and the critical point is:

    MapInfo builds attribute indexes row‑by‑row, not as a bulk post-process

     

    Dropping even one index can halve runtime.

    Avoid indexing text fields if at all possible

     

    Consider writing the geometry TAB with minimal attributes

    Write the attributes-only to a DBF

    Join the two in mapinfo downstream

      nicholas
      Contributor
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      • nicholasContributor
      • Author
      • Contributor
      • Feb 23, 2026 4:51 AM UTC

      Hi ​@j.botterill  from where do you get that quote?

      I have been reading the FME help docs on the Precisely MapInfo Extended TAB Writer and I cannot see a mention of “MapInfo builds attribute indexes row‑by‑row, not as a bulk post-process”

      But I may be looking in the wrong place

      j.botterill
      Evangelist
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      • j.botterillEvangelist
      • Evangelist
      • Feb 26, 2026 1:01 AM UTC

      I got that info from mapinfo sources about the format itself

      nicholas
      Contributor
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      • nicholasContributor
      • Author
      • Contributor
      • Feb 26, 2026 1:14 AM UTC

      I use MapInfo often, and it is absolutely possible to build an Index on a column after all the records have been inserted.

      For large datasets, a common optimisation is to drop the indexes, make the changes and then re-build the indexes.

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