Hi,

This is a question about the HBase transaction model.

Suppose I have a table with two columns "c1" and "c2". Now assume for each timestamp in each row, I have a entry in each column. That is, assume the table is ALWAYS written such that it is "dense" (e.g. a complete relation) rather than sparse (e.g. a partial relation) using the transaction semantics:

    HTable table = new HTable(conf, new Text("test"));
    static final Text rowId = new Text("row_num");
    static final Text col1Id = new Text("c1");
    static final Text col2Id = new Text("c2");

    long lockid = table.startUpdate(rowId);

    // always write all columns in a row
    table.put( lockid, col1Id, val );
    table.put( lockid, col2Id, val );

    table.commit( lockid, timestamp );

Also assume that  the two columns are read as something like:

    byte[][] c1Vals = table.get( rowId, col1Id, versions );
    byte[][] c2Vals = table.get( rowId, col2Id, versions );


Is it guaranteed that for each index value i, c1Vals[i][] and c2Vals[i][] are the two column entries originally written with the same timestamp?

Also, is something like:

    byte[][] c1Vals = table.get( rowId, col1Id, MAX_VALUE );

sufficient to guarantee all versions are returned in the "get" operations?

Thanks,
Rick


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