Google Bigtable v2 API - Class RowFilter (3.2.0)

Reference documentation and code samples for the Google Bigtable v2 API class RowFilter.

Takes a row as input and produces an alternate view of the row based on specified rules. For example, a RowFilter might trim down a row to include just the cells from columns matching a given regular expression, or might return all the cells of a row but not their values. More complicated filters can be composed out of these components to express requests such as, "within every column of a particular family, give just the two most recent cells which are older than timestamp X."

There are two broad categories of RowFilters (true filters and transformers), as well as two ways to compose simple filters into more complex ones (chains and interleaves). They work as follows:

• True filters alter the input row by excluding some of its cells wholesale from the output row. An example of a true filter is the value_regex_filter, which excludes cells whose values don't match the specified pattern. All regex true filters use RE2 syntax (https://github.com/google/re2/wiki/Syntax) in raw byte mode (RE2::Latin1), and are evaluated as full matches. An important point to keep in mind is that RE2(.) is equivalent by default to RE2([^\n]), meaning that it does not match newlines. When attempting to match an arbitrary byte, you should therefore use the escape sequence \C, which may need to be further escaped as \\C in your client language.

• Transformers alter the input row by changing the values of some of its cells in the output, without excluding them completely. Currently, the only supported transformer is the strip_value_transformer, which replaces every cell's value with the empty string.

• Chains and interleaves are described in more detail in the RowFilter.Chain and RowFilter.Interleave documentation.

The total serialized size of a RowFilter message must not exceed 20480 bytes, and RowFilters may not be nested within each other (in Chains or Interleaves) to a depth of more than 20.

Applies the given label to all cells in the output row. This allows the client to determine which results were produced from which part of the filter.

Values must be at most 15 characters in length, and match the RE2 pattern [a-z0-9\\-]+

Due to a technical limitation, it is not currently possible to apply multiple labels to a cell. As a result, a Chain may have no more than one sub-filter which contains a apply_label_transformer. It is okay for an Interleave to contain multiple apply_label_transformers, as they will be applied to separate copies of the input. This may be relaxed in the future.

Does not match any cells, regardless of input. Useful for temporarily disabling just part of a filter.

Matches only the most recent N cells within each column. For example, if N=2, this filter would match column foo:bar at timestamps 10 and 9, skip all earlier cells in foo:bar, and then begin matching again in column foo:bar2. If duplicate cells are present, as is possible when using an Interleave, each copy of the cell is counted separately.

Matches only the first N cells of each row. If duplicate cells are present, as is possible when using an Interleave, each copy of the cell is counted separately.

Skips the first N cells of each row, matching all subsequent cells. If duplicate cells are present, as is possible when using an Interleave, each copy of the cell is counted separately.

Applies several RowFilters to the data in sequence, progressively narrowing the results.

Matches only cells from columns whose qualifiers satisfy the given RE2 regex. Note that, since column qualifiers can contain arbitrary bytes, the \C escape sequence must be used if a true wildcard is desired. The . character will not match the new line character \n, which may be present in a binary qualifier.

Matches only cells from columns within the given range.

Applies one of two possible RowFilters to the data based on the output of a predicate RowFilter.

Matches only cells from columns whose families satisfy the given RE2 regex. For technical reasons, the regex must not contain the : character, even if it is not being used as a literal. Note that, since column families cannot contain the new line character \n, it is sufficient to use . as a full wildcard when matching column family names.

Applies several RowFilters to the data in parallel and combines the results.

Matches all cells, regardless of input. Functionally equivalent to leaving filter unset, but included for completeness.

Matches only cells from rows whose keys satisfy the given RE2 regex. In other words, passes through the entire row when the key matches, and otherwise produces an empty row. Note that, since row keys can contain arbitrary bytes, the \C escape sequence must be used if a true wildcard is desired. The . character will not match the new line character \n, which may be present in a binary key.

Matches all cells from a row with probability p, and matches no cells from the row with probability 1-p.

ADVANCED USE ONLY. Hook for introspection into the RowFilter. Outputs all cells directly to the output of the read rather than to any parent filter. Consider the following example:

Chain( FamilyRegex("A"), Interleave( All(), Chain(Label("foo"), Sink()) ), QualifierRegex("B") )

               A,A,1,w
               A,B,2,x
               B,B,4,z
                  |
           FamilyRegex("A")
                  |
               A,A,1,w
               A,B,2,x
                  |
     +------------+-------------+
     |                          |
   All()                    Label(foo)
     |                          |
  A,A,1,w              A,A,1,w,labels:[foo]
  A,B,2,x              A,B,2,x,labels:[foo]
     |                          |
     |                        Sink() --------------+
     |                          |                  |
     +------------+      x------+          A,A,1,w,labels:[foo]
                  |                        A,B,2,x,labels:[foo]
               A,A,1,w                             |
               A,B,2,x                             |
                  |                                |
          QualifierRegex("B")                      |
                  |                                |
               A,B,2,x                             |
                  |                                |
                  +--------------------------------+
                  |
               A,A,1,w,labels:[foo]
               A,B,2,x,labels:[foo]  // could be switched
               A,B,2,x               // could be switched

Despite being excluded by the qualifier filter, a copy of every cell that reaches the sink is present in the final result.

As with an [Interleave][google.bigtable.v2.RowFilter.Interleave], duplicate cells are possible, and appear in an unspecified mutual order. In this case we have a duplicate with column "A:B" and timestamp 2, because one copy passed through the all filter while the other was passed through the label and sink. Note that one copy has label "foo", while the other does not.

Cannot be used within the predicate_filter, true_filter, or false_filter of a [Condition][google.bigtable.v2.RowFilter.Condition].

Replaces each cell's value with the empty string.

Matches only cells with timestamps within the given range.

Matches only cells with values that fall within the given range.

Matches only cells with values that satisfy the given regular expression. Note that, since cell values can contain arbitrary bytes, the \C escape sequence must be used if a true wildcard is desired. The . character will not match the new line character \n, which may be present in a binary value.