Definition

Controls how def~tables are exposed to queriesGiven such flexible and comprehensive layout of data and rich def~timeline, Hudi is able to support three different ways of querying a def~table, depending on its def~table-type

Query Typedef~copy-on-write (COW)def~merge-on-read (MOR)
Snapshot QueryQuery is performed on the latest def~base-files across all def~file-slices in a given def~table or def~table-partition and will see records written upto the latest def~commit action.Query is performed by merging the latest def~base-file and its def~log-files across all def~file-slices in a given def~table or def~table-partition and will see records written upto the latest def~delta-commit action.
Incremental QueryQuery is performed on the latest def~base-file, within a given range of start , end  def~instant-times (called the incremental query window), while fetching only records that were written during this window by use of the def~hoodie-special-columnsQuery is performed on a latest def~file-slice within the incremental query window, using a combination of reading records out of base or log blocks, depending on the window itself.
Read Optimized QuerySame as snapshot queryOnly access the def~base-file, providing data as of the last def~compaction action performed on a given def~file-slice. In general, guarantees of how fresh/upto date the queried data is, depends on def~compaction-policy





Related concepts

  1. def~read-optimized-query
  2. def~incremental-query
  3. def~snapshot-query
  4. def~timeline
  5. def~table
  6. def~commit
  7. def~table-type


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1 Comment

  1. SemanticBeeng

    Feb 10, 2020

    Please define all the concepts referenced in this page Vinoth Chandar.

    If you can also be extra kind to reference code matching them the would be awesome. (smile)