module Google::Cloud::Bigtable::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 (#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()`, 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.
@example
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
Constants
- BLOCK
@private
- PASS
@private
- SINK
@private
- STRIP_VALUE
@private
Public Class Methods
Creates a block-all filter instance.
Does not match any cells, regardless of input. Useful for temporarily disabling just part of a filter.
@return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.block
# File lib/google/cloud/bigtable/row_filter.rb, line 313 def self.block BLOCK end
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.
@param limit [String] Max cell match per column limit @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.cells_per_column 5
# File lib/google/cloud/bigtable/row_filter.rb, line 547 def self.cells_per_column limit SimpleFilter.new.cells_per_column limit end
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.
@param limit [String] Max cell match per row limit @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.cells_per_row 5
# File lib/google/cloud/bigtable/row_filter.rb, line 528 def self.cells_per_row limit SimpleFilter.new.cells_per_row limit end
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.
@param offset [Integer] Offset value. @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.cells_per_row_offset 3
# 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
Creates a chain filter instance.
A chain RowFilter
that sends rows through several RowFilters in sequence.
See {Google::Cloud::Bigtable::RowFilter::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.
@return [Google::Cloud::Bigtable::RowFilter::ChainFilter]
@example 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
@example 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-*")
# File lib/google/cloud/bigtable/row_filter.rb, line 186 def self.chain ChainFilter.new end
Creates a column-range filter instance.
Matches only cells from columns within the given range.
@param range [Google::Cloud::Bigtable::ColumnRange] @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" range = Google::Cloud::Bigtable::ColumnRange.new("cf").from("field0").to("field5") filter = Google::Cloud::Bigtable::RowFilter.column_range range
# File lib/google/cloud/bigtable/row_filter.rb, line 633 def self.column_range range SimpleFilter.new.column_range range end
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`.
@param predicate [SimpleFilter, ChainFilter
, InterleaveFilter
, ConditionFilter] @return [Google::Cloud::Bigtable::RowFilter::ConditionFilter]
@example
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)
# File lib/google/cloud/bigtable/row_filter.rb, line 279 def self.condition predicate ConditionFilter.new predicate end
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.
@see github.com/google/re2/wiki/Syntax Regex syntax
@param regex [String] Regex to match family name. @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.family "cf-.*"
# File lib/google/cloud/bigtable/row_filter.rb, line 414 def self.family regex SimpleFilter.new.family regex end
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.
@return [Google::Cloud::Bigtable::RowFilter::InterleaveFilter]
@example 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
@example 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-*")
# File lib/google/cloud/bigtable/row_filter.rb, line 247 def self.interleave InterleaveFilter.new end
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.
@see github.com/google/re2/wiki/Syntax Regex syntax
@param regex [String] Regex to match row keys. @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.key "user-.*"
# File lib/google/cloud/bigtable/row_filter.rb, line 371 def self.key regex SimpleFilter.new.key regex end
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.
@param value [String] Label name @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.label "user-detail"
# File lib/google/cloud/bigtable/row_filter.rb, line 490 def self.label value SimpleFilter.new.label value end
Creates a pass filter instance.
Matches all cells, regardless of input. Functionally equivalent to leaving `filter` unset, but included for completeness.
@return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.pass
# File lib/google/cloud/bigtable/row_filter.rb, line 296 def self.pass PASS end
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.
@see github.com/google/re2/wiki/Syntax Regex syntax
@param regex [String] Regex to match column qualifier name. @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.qualifier "user-name.*"
# File lib/google/cloud/bigtable/row_filter.rb, line 438 def self.qualifier regex SimpleFilter.new.qualifier regex end
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.
@param probability [Float] Probability value.
Probability must be greater than 0 and less than 1.0.
@return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.sample 0.5
# File lib/google/cloud/bigtable/row_filter.rb, line 390 def self.sample probability SimpleFilter.new.sample probability end
Creates a sink filter instance.
Outputs all cells directly to the output of the read rather than to any parent filter.
@return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.sink
# File lib/google/cloud/bigtable/row_filter.rb, line 330 def self.sink SINK end
Creates a strip value filter instance.
Replaces each cell's value with an empty string.
@return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.strip_value
# File lib/google/cloud/bigtable/row_filter.rb, line 346 def self.strip_value STRIP_VALUE end
Creates a timestamp-range filter instance.
Matches only cells with timestamps within the given range. Specifies a contiguous range of timestamps.
@param from [Integer] Inclusive lower bound. If left empty, interpreted as 0. @param to [Integer] Exclusive upper bound. If left empty, interpreted as infinity. @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
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
# 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
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.
@see github.com/google/re2/wiki/Syntax Regex syntax
@param regex [String] Regex to match cell value. @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example
require "google/cloud/bigtable" filter = Google::Cloud::Bigtable::RowFilter.value "abc.*"
# File lib/google/cloud/bigtable/row_filter.rb, line 461 def self.value regex SimpleFilter.new.value regex end
Creates a value-range filter instance.
Matches only cells with values that fall within the given range.
See {Google::Cloud::Bigtable::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.
@param range [Google::Cloud::Bigtable::ValueRange] @return [Google::Cloud::Bigtable::RowFilter::SimpleFilter]
@example 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
@example 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
# File lib/google/cloud/bigtable/row_filter.rb, line 614 def self.value_range range SimpleFilter.new.value_range range end