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  1. Calcite
  2. CALCITE-270

Generate complex conditions against MongoDB

    Details

    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: mongodb
    • Labels:

      Description

      We need to rework the MongoDB adapter to support complex conditions. Currently we use the `$match` operator whose syntax is limiting because it expects a column name on the LHS and a value on the RHS.

      We should instead generate a 'condition' column to be preceding `$project` operator. Then we can generate expressions the conventional way, e.g. `$gt: [e1, e2]` as opposed to `e1: {$gt: e2}`.

      In the following example, `cond` holds the evaluated condition, a subsequent `$match` filters on it, then a `$project` projects away the column.

      ```json
      db.zips.aggregate(
      {$project: {STATE: '$state', POP: '$pop'}},
      {$group: {_id: '$STATE', C: {$sum: 1}, _2: {$sum: '$POP'}}},
      {$project: {STATE: '$_id', C: '$C', _2: '$_2', cond: {$gt: [{$cond: [{$eq: ["$C", 0]}, null, "$_2"]}, 12000000]}}},
      {$match: {cond: true}},
      {$project: {STATE: 1, C: 1}})
      ```

      ---------------- Imported from GitHub ----------------
      Url: https://github.com/julianhyde/optiq/issues/270
      Created by: julianhyde
      Labels:
      Created at: Thu May 01 23:37:10 CEST 2014
      State: open

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