Module: Google::Cloud::Bigtable::RowFilter

Defined in:
lib/google/cloud/bigtable/row_filter.rb,
lib/google/cloud/bigtable/row_filter/chain_filter.rb,
lib/google/cloud/bigtable/row_filter/simple_filter.rb,
lib/google/cloud/bigtable/row_filter/condition_filter.rb,
lib/google/cloud/bigtable/row_filter/interleave_filter.rb

Overview

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 it 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 that are older than timestamp X."

Two broad categories of RowFilters are true filters and transformers. Two ways to compose simple filters into more complex ones are 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 should be further escaped as \\C in Ruby.

  • 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 an 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 4096 bytes, and RowFilters may not be nested within each other (in chains or interleaves) to a depth of more than 20.

ADVANCED USE:. 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 filter, 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 filters. Note that one copy has the label "foo", while the other does not.

Examples:

require "google/cloud/bigtable"

# Pass filter
Google::Cloud::Bigtable::RowFilter.pass

# Key regex filter
Google::Cloud::Bigtable::RowFilter.key "user-*"

# Cell limit filter
Google::Cloud::Bigtable::RowFilter.cells_per_row 10

Defined Under Namespace

Classes: ChainFilter, ConditionFilter, InterleaveFilter, SimpleFilter

Class Method Summary collapse

Class Method Details

.block ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a block-all filter instance.

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

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.block

Returns:



313
314
315
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 313

def self.block
  BLOCK
end

.cells_per_column(limit) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates cells-per-column filter instance.

Matches only the most recent N cells within each column. If duplicate cells are present, as is possible when using an interleave, each copy of the cell is counted separately.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.cells_per_column 5

Parameters:

  • limit (String) —

    Max cell match per column limit

Returns:



547
548
549
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 547

def self.cells_per_column limit
  SimpleFilter.new.cells_per_column limit
end

.cells_per_row(limit) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Create a cells-per-row limit filter instance.

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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.cells_per_row 5

Parameters:

  • limit (String) —

    Max cell match per row limit

Returns:



528
529
530
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 528

def self.cells_per_row limit
  SimpleFilter.new.cells_per_row limit
end

.cells_per_row_offset(offset) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a cell-per-row-offset filter instance to skip first N cells.

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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.cells_per_row_offset 3

Parameters:

  • offset (Integer) —

    Offset value.

Returns:



509
510
511
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 509

def self.cells_per_row_offset offset
  SimpleFilter.new.cells_per_row_offset offset
end

.chain ⇒ Google::Cloud::Bigtable::RowFilter::ChainFilter

Creates a chain filter instance.

A chain RowFilter that sends rows through several RowFilters in sequence.

See ChainFilter.

The elements of "filters" are chained together to process the input row: in row -> f(0) -> intermediate row -> f(1) -> ... -> f(N) -> out row The full chain is executed atomically.

Examples:

Create chain filter with simple filter.

require "google/cloud/bigtable"

chain = Google::Cloud::Bigtable::RowFilter.chain

# Add filters to chain filter
chain.key "user-*"
chain.strip_value

# OR
chain.key("user-*").strip_value

Create complex chain filter.

require "google/cloud/bigtable"

chain = Google::Cloud::Bigtable::RowFilter.chain

chain_1 = Google::Cloud::Bigtable::RowFilter.chain
chain_1.label("users").qualifier("name").cells_per_row(5)

# Add to main chain filter
chain.chain(chain_1).value("xyz*").key("user-*")

Returns:



186
187
188
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 186

def self.chain
  ChainFilter.new
end

.column_range(range) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a column-range filter instance.

Matches only cells from columns within the given range.

Examples:

require "google/cloud/bigtable"

range = Google::Cloud::Bigtable::ColumnRange.new("cf").from("field0").to("field5")

filter = Google::Cloud::Bigtable::RowFilter.column_range range

Parameters:

Returns:



633
634
635
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 633

def self.column_range range
  SimpleFilter.new.column_range range
end

.condition(predicate) ⇒ Google::Cloud::Bigtable::RowFilter::ConditionFilter

Creates a condition filter instance.

A RowFilter that evaluates one of two possible RowFilters, depending on whether or not a predicate RowFilter outputs any cells from the input row.

IMPORTANT NOTE: The predicate filter does not execute atomically with the true and false filters, which may lead to inconsistent or unexpected results. Additionally, condition filters have poor performance, especially when filters are set for the false condition.

Cannot be used within the predicate_filter, true_filter, or false_filter.

Examples:

require "google/cloud/bigtable"

predicate = Google::Cloud::Bigtable::RowFilter.key "user-*"
condition = Google::Cloud::Bigtable::RowFilter.condition predicate

label = Google::Cloud::Bigtable::RowFilter.label "user"
strip_value = Google::Cloud::Bigtable::RowFilter.strip_value

# On match apply label, else strip cell values
condition.on_match(label).otherwise(strip_value)

Parameters:

Returns:



279
280
281
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 279

def self.condition predicate
  ConditionFilter.new predicate
end

.family(regex) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a family name match filter using a regular expression.

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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.family "cf-.*"

Parameters:

  • regex (String) —

    Regex to match family name.

Returns:

See Also:



414
415
416
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 414

def self.family regex
  SimpleFilter.new.family regex
end

.interleave ⇒ Google::Cloud::Bigtable::RowFilter::InterleaveFilter

Creates an interleave filter.

A RowFilter that sends each row to each of several component RowFilters and interleaves the results.

The elements of "filters" all process a copy of the input row, and the results are pooled, sorted, and combined into a single output row. If multiple cells are produced with the same column and timestamp, they will all appear in the output row in an unspecified mutual order. Consider the following example, with three filters:

                             input row
                                 |
       -----------------------------------------------------
       |                         |                         |
      f(0)                      f(1)                      f(2)
       |                         |                         |
1: foo,bar,10,x             foo,bar,10,z              far,bar,7,a
2: foo,blah,11,z            far,blah,5,x              far,blah,5,x
       |                         |                         |
       -----------------------------------------------------
                                 |
1:                      foo,bar,10,z   # could have switched with #2
2:                      foo,bar,10,x   # could have switched with #1
3:                      foo,blah,11,z
4:                      far,bar,7,a
5:                      far,blah,5,x   # identical to #6
6:                      far,blah,5,x   # identical to #5

All interleaved filters are executed atomically.

Examples:

Create an interleave filter with simple filter.

require "google/cloud/bigtable"

interleave = Google::Cloud::Bigtable::RowFilter.interleave

# Add filters to interleave filter
interleave.key "user-*"
interleave.sink

# OR
interleave.key("user-*").sink

Create complex interleave filter.

require "google/cloud/bigtable"

interleave = Google::Cloud::Bigtable::RowFilter.interleave

chain_1 = Google::Cloud::Bigtable::RowFilter.chain
chain_1.label("users").qualifier("name").cells_per_row(5)

# Add to main chain filter
interleave.chain(chain_1).value("xyz*").key("user-*")

Returns:



247
248
249
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 247

def self.interleave
  InterleaveFilter.new
end

.key(regex) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a key filter instance to match a row key using a regular expression.

Matches only cells from rows whose row 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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.key "user-.*"

Parameters:

  • regex (String) —

    Regex to match row keys.

Returns:

See Also:



371
372
373
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 371

def self.key regex
  SimpleFilter.new.key regex
end

.label(value) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a label filter instance to apply a label based on the result of read rows.

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 and match the RE2 pattern [a-z0-9\\-]+

Due to a technical limitation, it is not possible to apply multiple labels to a cell. As a result, a chain may have no more than one sub-filter that contains an 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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.label "user-detail"

Parameters:

  • value (String) —

    Label name

Returns:



490
491
492
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 490

def self.label value
  SimpleFilter.new.label value
end

.pass ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a pass filter instance.

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

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.pass

Returns:



296
297
298
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 296

def self.pass
  PASS
end

.qualifier(regex) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a column qualifier match filter using a regular expression.

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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.qualifier "user-name.*"

Parameters:

  • regex (String) —

    Regex to match column qualifier name.

Returns:

See Also:



438
439
440
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 438

def self.qualifier regex
  SimpleFilter.new.qualifier regex
end

.sample(probability) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a sample probability filter instance.

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

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.sample 0.5

Parameters:

  • probability (Float) —

    Probability value. Probability must be greater than 0 and less than 1.0.

Returns:



390
391
392
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 390

def self.sample probability
  SimpleFilter.new.sample probability
end

.sink ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a sink filter instance.

Outputs all cells directly to the output of the read rather than to any parent filter.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.sink

Returns:



330
331
332
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 330

def self.sink
  SINK
end

.strip_value ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a strip value filter instance.

Replaces each cell's value with an empty string.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.strip_value

Returns:



346
347
348
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 346

def self.strip_value
  STRIP_VALUE
end

.timestamp_range(from: nil, to: nil) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a timestamp-range filter instance.

Matches only cells with timestamps within the given range. Specifies a contiguous range of timestamps.

Examples:

require "google/cloud/bigtable"

timestamp_micros = (Time.now.to_f * 1_000_000).round(-3)
from = timestamp_micros - 300_000_000
to = timestamp_micros

filter = Google::Cloud::Bigtable::RowFilter.timestamp_range from: from, to: to

# From to infinity
filter = Google::Cloud::Bigtable::RowFilter.timestamp_range from: from

# From 0 value to `to`
filter = Google::Cloud::Bigtable::RowFilter.timestamp_range to: to

Parameters:

  • from (Integer) (defaults to: nil) —

    Inclusive lower bound. If left empty, interpreted as 0.

  • to (Integer) (defaults to: nil) —

    Exclusive upper bound. If left empty, interpreted as infinity.

Returns:



576
577
578
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 576

def self.timestamp_range from: nil, to: nil
  SimpleFilter.new.timestamp_range from, to
end

.value(regex) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a value match filter using a regular expression.

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.

Examples:

require "google/cloud/bigtable"

filter = Google::Cloud::Bigtable::RowFilter.value "abc.*"

Parameters:

  • regex (String) —

    Regex to match cell value.

Returns:

See Also:



461
462
463
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 461

def self.value regex
  SimpleFilter.new.value regex
end

.value_range(range) ⇒ Google::Cloud::Bigtable::RowFilter::SimpleFilter

Creates a value-range filter instance.

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

See ValueRange#from and { Google::Cloud::Bigtable::ValueRange#to} for range option inclusive/exclusive options

  • The value at which to start the range. If neither field is set, interpreted as an empty string, inclusive.
  • The value at which to end the range. If neither field is set, interpreted as an infinite string, exclusive.

Examples:

Start to end range.

require "google/cloud/bigtable"

bigtable = Google::Cloud::Bigtable.new
table = bigtable.table "my-instance", "my-table"

range = table.new_value_range.from "value-001", inclusive: false
filter = Google::Cloud::Bigtable::RowFilter.value_range range

Start exclusive to infinite end range.

require "google/cloud/bigtable"

bigtable = Google::Cloud::Bigtable.new
table = bigtable.table "my-instance", "my-table"

range = table.new_value_range.from "value-001", inclusive: false
filter = Google::Cloud::Bigtable::RowFilter.value_range range

Parameters:

Returns:



614
615
616
 
# File 'lib/google/cloud/bigtable/row_filter.rb', line 614

def self.value_range range
  SimpleFilter.new.value_range range
end