Class: RdfContext::AbstractSQLStore

Inherits:
AbstractStore show all
Includes:
TermUtils
Defined in:
lib/rdf_context/store/abstract_sql_store.rb

Overview

SQL-92 formula-aware implementation of an RDF Store. It stores it’s triples in the following partitions:

  • Asserted non rdf:type statements

  • Asserted literal statements

  • Asserted rdf:type statements (in a table which models Class membership). The motivation for this partition is primarily query speed and scalability as most graphs will always have more rdf:type statements than others

  • All Quoted statements

In addition it persists namespace mappings in a seperate table

Based on Python RdfLib AbstractSQLStore

Direct Known Subclasses

ActiveRecordStore, SQLite3Store

Constant Summary collapse

COUNT_SELECT = 
0
CONTEXT_SELECT = 
1
TRIPLE_SELECT = 
2
TRIPLE_SELECT_NO_ORDER = 
3
ASSERTED_NON_TYPE_PARTITION = 
3
ASSERTED_TYPE_PARTITION = 
4
QUOTED_PARTITION = 
5
ASSERTED_LITERAL_PARTITION = 
6
FULL_TRIPLE_PARTITIONS = 
[QUOTED_PARTITION,ASSERTED_LITERAL_PARTITION]
INTERNED_PREFIX = 
'kb_'
STRONGLY_TYPED_TERMS = 
false

Constants included from TermUtils

TermUtils::CONTEXT, TermUtils::GRAPH_TERM_DICT, TermUtils::OBJECT, TermUtils::PREDICATE, TermUtils::REVERSE_TERM_COMBINATIONS, TermUtils::SUBJECT, TermUtils::TERM_COMBINATIONS, TermUtils::TERM_INSTANTIATION_DICT

Instance Attribute Summary

Attributes inherited from AbstractStore

#identifier

Instance Method Summary collapse

Methods included from TermUtils

#constructGraph, #normalizeGraph, #statement2TermCombination, #term2Letter, #type2TermCombination

Methods inherited from AbstractStore

#bnodes, #inspect, #item, #objects, #open, #predicates, #subjects

Constructor Details

#initialize(identifier = nil, configuration = {}) ⇒ AbstractSQLStore

Create a new AbstractSQLStore Store, should be subclassed @param configuration Specific to type of storage

Parameters:

  • identifier (URIRef) (defaults to: nil)

Raises:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 39

def initialize(identifier = nil, configuration = {})
  @literalCache = {}
  @otherCache = {}
  @bnodeCache = {}
  @uriCache = {}
  
  @autocommit_default = true
  
  raise StoreException.new("Identifier must be nil or a URIRef") if identifier && !identifier.is_a?(URIRef)
  @identifier = identifier || URIRef.new("file:/#{Dir.getwd}")
  
  @internedId = INTERNED_PREFIX + Digest::SHA1.hexdigest(@identifier.to_s)[0..9] # Only first 10 bytes of digeset
  
  @db = configuration.empty? ? nil : open(configuration)
end

Instance Method Details

#_normalizeSQLCmd(cmd) ⇒ Object (protected)

Normalize a SQL command before executing it. Commence unicode black magic



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 663

def _normalizeSQLCmd(cmd)
  cmd # XXX
end

#add(triple, context = nil, quoted = false) ⇒ Triple

Add a triple to the store Add to default context, if context is nil

Parameters:

  • triple (Triple)
  • context (Graph) (defaults to: nil) —

    (nil)

  • quoted (Boolean) (defaults to: false) —

    (false) A quoted triple, for Formulae

Returns:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 90

def add(triple, context = nil, quoted = false)
  context ||= @identifier
  executeSQL("SET AUTOCOMMIT=0") if @autocommit_default
  
  if quoted || triple.predicate != RDF_TYPE
    # Quoted statement or non rdf:type predicate
    # Check if object is a literal
    if triple.object.is_a?(Literal)
      addCmd, *params = self.buildLiteralTripleSQLCommand(triple, context)
    else
      addCmd, *params = self.buildTripleSQLCommand(triple, context, quoted)
    end
  elsif triple.predicate == RDF_TYPE
    addCmd, *params = self.buildTypeSQLCommand(triple.subject, triple.object, context)
  end
  
  executeSQL(addCmd, params)
end

#asserted_table ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 635

def asserted_table; "#{@internedId}_asserted_statements"; end

#asserted_type_table ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 636

def asserted_type_table; "#{@internedId}_type_statements"; end

#bind(namespace) ⇒ Namespace

Namespace persistence interface implementation

Bind namespace to store, returns bound namespace

Parameters:

  • namespace (Nameespace) —

    the namespace to bind

Returns:

  • (Namespace) —

    The newly bound or pre-existing namespace.



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 554

def bind(namespace)
  # Remove existing bindings for the same URI
  executeSQL("DELETE FROM #{namespace_binds} WHERE prefix=?", namespace.prefix.to_s)
  executeSQL("INSERT INTO #{namespace_binds} VALUES (?, ?)", namespace.prefix.to_s, namespace.uri.to_s)
  # May throw exception, should be handled in driver-specific class

  @namespaceCache ||= {}
  @namespaceUriCache ||= {}
  @nsbinding = nil
  @uri_binding = nil
  @namespaceCache[namespace.prefix] = namespace
  @namespaceUriCache[namespace.uri.to_s] = namespace.prefix
  namespace
end

#buildClause(tableName, triple, context = nil, typeTable = false) ⇒ Object (protected)

Builds WHERE clauses for the supplied terms and, context



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 736

def buildClause(tableName,triple,context=nil,typeTable=false)
  parameters=[]
  if typeTable
    rdf_type_memberClause = rdf_type_klassClause = rdf_type_contextClause = nil

    # Subject clause
    clauseParts = self.buildTypeMemberClause(self.normalizeTerm(triple.subject),tableName)
    if clauseParts
      rdf_type_memberClause = clauseParts.shift
      parameters += clauseParts
    end

    # Object clause
    clauseParts = self.buildTypeClassClause(self.normalizeTerm(triple.object),tableName)
    if clauseParts
      rdf_type_klassClause = clauseParts.shift
      parameters += clauseParts
    end

    # Context clause
    clauseParts = self.buildContextClause(context,tableName)
    if clauseParts
      rdf_type_contextClause = clauseParts.shift
      parameters += clauseParts
    end

    clauses = [rdf_type_memberClause,rdf_type_klassClause,rdf_type_contextClause].compact
  else
    subjClause = predClause = objClause = contextClause = litDTypeClause = litLanguageClause = nil

    # Subject clause
    clauseParts = self.buildSubjClause(self.normalizeTerm(triple.subject),tableName)
    if clauseParts
      subjClause = clauseParts.shift
      parameters += clauseParts
    end

    # Predicate clause
    clauseParts = self.buildPredClause(self.normalizeTerm(triple.predicate),tableName)
    if clauseParts
      predClause = clauseParts.shift
      parameters += clauseParts
    end

    # Object clause
    clauseParts = self.buildObjClause(self.normalizeTerm(triple.object),tableName)
    if clauseParts
      objClause = clauseParts.shift
      parameters += clauseParts
    end

    # Context clause
    clauseParts = self.buildContextClause(context,tableName)
    if clauseParts
      contextClause = clauseParts.shift
      parameters += clauseParts
    end

    # Datatype clause
    clauseParts = self.buildLitDTypeClause(triple.object,tableName)
    if clauseParts
      litDTypeClause = clauseParts.shift
      parameters += clauseParts
    end

    # Language clause
    clauseParts = self.buildLitLanguageClause(triple.object,tableName)
    if clauseParts
      litLanguageClause = clauseParts.shift
      parameters += clauseParts
    end
    
    clauses = [subjClause,predClause,objClause,contextClause,litDTypeClause,litLanguageClause].compact
  end

  clauseString = clauses.join(' and ')
  clauseString = "WHERE #{clauseString}" unless clauseString.empty?
  
  [clauseString] + parameters
end

#buildContextClause(context, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 829

def buildContextClause(context,tableName); end

#buildLitDTypeClause(obj, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 817

def buildLitDTypeClause(obj,tableName)
  ["#{tableName}.objDatatype='#{obj.encoding.value}'"] if obj.is_a?(Literal) && obj.encoding
end

#buildLiteralTripleSQLCommand(triple, context) ⇒ Object (protected)

Builds an insert command for literal triples (statements where the object is a Literal) Returns string and list of parameters



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 693

def buildLiteralTripleSQLCommand(triple,context)
  triplePattern = statement2TermCombination(triple,context)
  [
    "INSERT INTO #{literal_table} VALUES (?, ?, ?, ?, ?,?,?)",
    normalizeTerm(triple.subject),
    normalizeTerm(triple.predicate),
    normalizeTerm(triple.object),
    normalizeTerm(context),
    triplePattern,
    (triple.object.is_a?(Literal) && triple.object.lang ? triple.object.lang.to_s : nil),
    (triple.object.is_a?(Literal) && triple.object.encoding ? triple.object.encoding.value.to_s : nil),
  ]
end

#buildLitLanguageClause(obj, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 821

def buildLitLanguageClause(obj,tableName)
  ["#{tableName}.objLanguage='#{obj.lang}'"] if obj.is_a?(Literal) && obj.lang
end

#buildObjClause(obj, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 828

def buildObjClause(obj,tableName); end

#buildPredClause(predicate, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 827

def buildPredClause(predicate,tableName); end

#buildSubjClause(subject, tableName) ⇒ Object (protected)

Stubs for Clause Functions that are overridden by specific implementations (MySQL vs SQLite for instance)



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 826

def buildSubjClause(subject,tableName); end

#buildTripleSQLCommand(triple, context, quoted) ⇒ Object (protected)

Builds an insert command for regular triple table



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 708

def buildTripleSQLCommand(triple,context,quoted)
  stmt_table = quoted ? quoted_table : asserted_table
  triplePattern = statement2TermCombination(triple,context)

  if quoted
    [
      "INSERT INTO #{stmt_table} VALUES (?, ?, ?, ?, ?,?,?)",
      normalizeTerm(triple.subject),
      normalizeTerm(triple.predicate),
      normalizeTerm(triple.object),
      normalizeTerm(context),
      triplePattern,
      (triple.object.is_a?(Literal) && triple.object.lang ? triple.object.lang.to_s : nil),
      (triple.object.is_a?(Literal) && triple.object.encoding ? triple.object.encoding.value.to_s : nil),
    ]
  else
    [
      "INSERT INTO #{stmt_table} VALUES (?, ?, ?, ?, ?)",
      normalizeTerm(triple.subject),
      normalizeTerm(triple.predicate),
      normalizeTerm(triple.object),
      normalizeTerm(context),
      triplePattern
    ]
  end
end

#buildTypeClassClause(obj, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 831

def buildTypeClassClause(obj,tableName); end

#buildTypeMemberClause(subject, tableName) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 830

def buildTypeMemberClause(subject,tableName); end

#buildTypeSQLCommand(member, klass, context) ⇒ Object (protected)

Builds an insert command for a type table Returns string and list of parameters



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 681

def buildTypeSQLCommand(member,klass,context)
  [
    "INSERT INTO #{asserted_type_table} VALUES (?, ?, ?, ?)",
    normalizeTerm(member),
    normalizeTerm(klass),
    normalizeTerm(context),
    type2TermCombination(member, klass, context)
  ]
end

#close(commit_pending_transactions = false)

This method returns an undefined value.

Close the store

Parameters:

  • commit_pending_transactions (Boolean) (defaults to: false) —

    (false)



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 70

def close(commit_pending_transactions = false)
  @db.commit if commit_pending_transactions && @db.transaction_active?
  @db.close
end

#commit ⇒ Object

Transactional interfaces



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 629

def commit; @db.commit; end

#contains?(triple, context = nil) ⇒ Boolean

Check to see if this store contains the specified triple

Parameters:

  • triple (Triple)
  • context (Graph) (defaults to: nil) —

    (nil)

Returns:

  • (Boolean) 


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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 303

def contains?(triple, context = nil)
  #puts "contains? #{triple}"
  object = triple.object
  if object.is_a?(Literal)
    triple = Triple.new(triple.subject, triple.predicate, nil)
    triples(triple, context) do |t, cg|
      return true if t.object == object
    end
    false
  else
    !triples(triple, context).empty?
  end
end

#context_aware? ⇒ true

Supports contexts

Returns:

  • (true) 


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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 57

def context_aware?; true; end

#contexts(triple = nil) ⇒ Array<Graph>

Contexts containing the triple (no matching), or total number of contexts in store

Parameters:

  • triple (Triple) (defaults to: nil) —

    (nil) Containing the triple/pattern if not nil

Returns:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 410

def contexts(triple = nil)
  parameters = []
  
  if triple
    subject, predicate, object = triple.subject, triple.predicate, triple.object
    if predicate == RDF_TYPE
      # select from asserted rdf:type partition and quoted table (if a context is specified)
      clauseString, *params = self.buildClause('typeTable',triple,nil, true)
      parameters += params
      selects = [
        [
          asserted_type_table,
          'typeTable',
          clauseString,
          ASSERTED_TYPE_PARTITION
        ],
      ]
    #elsif predicate.is_a?(REGEXTerm) && predicate.compiledExpr.match(RDF_TYPE) || predicate.nil?
    elsif predicate.nil?
      # Select from quoted partition (if context is specified), literal partition if (obj is Literal or None) and asserted non rdf:type partition (if obj is URIRef or None)
      clauseString, *params = self.buildClause('typeTable',Triple.new(subject, RDF_TYPE, object),nil, true)
      parameters += params
      selects = [
        [
          asserted_type_table,
          'typeTable',
          clauseString,
          ASSERTED_TYPE_PARTITION
        ],
      ]

      if !STRONGLY_TYPED_TERMS || triple.object.is_a?(Literal) || triple.object.nil?
        clauseString, *params = self.buildClause('literal',triple)
        parameters += params
        selects += [
          [
            literal_table,
            'literal',
            clauseString,
            ASSERTED_LITERAL_PARTITION
          ]
        ]
      end
      if !object.is_a?(Literal) || object.nil?
        clauseString, *params = self.buildClause('asserted',triple)
        parameters += params
        selects += [
          [
            asserted_table,
            'asserted',
            clauseString,
            ASSERTED_NON_TYPE_PARTITION
          ]
        ]
      end
    elsif predicate
      # select from asserted non rdf:type partition (optionally), quoted partition (if context is speciied), and literal partition (optionally)
      selects = []
      if !STRONGLY_TYPED_TERMS || object.is_a?(Literal) || object.nil?
        clauseString, *params = self.buildClause('literal',triple)
        parameters += params
        selects += [
          [
            literal_table,
            'literal',
            clauseString,
            ASSERTED_LITERAL_PARTITION
          ]
        ]
      end
      if !object.is_a?(Literal) || object.nil?
        clauseString, *params = self.buildClause('asserted',triple)
        parameters += params
        selects += [
          [
            asserted_table,
            'asserted',
            clauseString,
            ASSERTED_NON_TYPE_PARTITION
          ]
        ]
      end
    end

    clauseString, *params = self.buildClause('quoted',triple)
    parameters += params
    selects += [
      [
        quoted_table,
        'quoted',
        clauseString,
        QUOTED_PARTITION
      ]
    ]
  else
    selects = [
      [
        asserted_type_table,
        'typeTable',
        '',
        ASSERTED_TYPE_PARTITION
      ],
      [
        quoted_table,
        'quoted',
        '',
        QUOTED_PARTITION
      ],
      [
        asserted_table,
        'asserted',
        '',
        ASSERTED_NON_TYPE_PARTITION
      ],
      [
        literal_table,
        'literal',
        '',
        ASSERTED_LITERAL_PARTITION
      ],
    ]
  end

  q=unionSELECT(selects, :distinct => true, :select_type => CONTEXT_SELECT)
  executeSQL(_normalizeSQLCmd(q), parameters).map do |row|
    id, termComb = row

    termCombString = REVERSE_TERM_COMBINATIONS[termComb.to_i]
    subjTerm, predTerm, objTerm, ctxTerm = termCombString.scan(/./)

    graphKlass, idKlass = constructGraph(ctxTerm)
    [graphKlass, idKlass.new(id)]
  end.uniq.map do |gi|
    graphKlass, id = gi
    graphKlass.new(:store => self, :identifier => id)
  end
end

#createTerm(termString, termType, objLanguage = nil, objDatatype = nil) ⇒ Object (protected)

Takes a term value, and term type and Creates a term object. QuotedGraphs are instantiated differently



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 915

def createTerm(termString,termType,objLanguage=nil,objDatatype=nil)
  #puts "createTerm(#{termString}, #{termType}, ...)" if ::RdfContext::debug?
  case termType
  when "L"
    @literalCache[[termString, objLanguage, objDatatype]] ||= Literal.n3_encoded(termString, objLanguage, objDatatype)
  when "F"
    @otherCache[[termType, termString]] ||= QuotedGraph(:identifier => URIRef(termString), :store => self)
  when "B"
    @bnodeCache[termString] ||= begin
      bn = BNode.new
      bn.identifier = termString
      bn
    end
  when "U"
    @uriCache[termString] || URIRef.new(termString)
#      when "V"
  else
    raise StoreException.new("Unknown termType: #{termType}")
  end
end

#destroy(configuration = {}) ⇒ Object

Destroy store or context If context is specified remove that context, otherwise, remove all triples

Parameters:

  • configuration (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (configuration):

  • :context (Graph) —

    Remove the specified context



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 79

def destroy(configuration = {})
  remove(Triple.new(nil, nil, nil), configuration[:context])
end

#executeSQL(qStr, *params, &block) ⇒ Object (protected)

This takes the query string and parameters and (depending on the SQL implementation) either fill in the parameter in-place or pass it on to the DB impl (if it supports this). The default (here) is to fill the parameters in-place surrounding each param with quote characters

Yields each row



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 658

def executeSQL(qStr, *params, &block)
  @db.execute(qStr, *params, &block)
end

#extractTriple(tupleRt, hardCodedContext = nil) ⇒ Object (protected)

Takes a tuple which represents an entry in a result set and converts it to a tuple of terms using the termComb integer to interpret how to instanciate each term tupleRt is an array containing one or more of:

  • subject

  • predicate

  • obj

  • rtContext

  • termComb

  • objLanguage

  • objDatatype

Raises:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 896

def extractTriple(tupleRt, hardCodedContext = nil)
  subject, predicate, obj, rtContext, termComb, objLanguage, objDatatype = tupleRt

  raise StoreException, "extractTriple: unknow termComb: '#{termComb}'" unless REVERSE_TERM_COMBINATIONS.has_key?(termComb.to_i)

  context = rtContext || hardCodedContext
  termCombString = REVERSE_TERM_COMBINATIONS[termComb.to_i]
  subjTerm, predTerm, objTerm, ctxTerm = termCombString.scan(/./)
  
  s = createTerm(subject, subjTerm)
  p = createTerm(predicate, predTerm)
  o = createTerm(obj, objTerm, objLanguage, objDatatype)

  graphKlass, idKlass = constructGraph(ctxTerm)
  return [Triple.new(s, p, o), graphKlass, idKlass, context]
end

#formula_aware? ⇒ true

Supports formulae

Returns:

  • (true) 


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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 61

def formula_aware?; true; end

#literal_table ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 637

def literal_table; "#{@internedId}_literal_statements"; end

#namespace(prefix) ⇒ Namespace

Namespace for prefix

Parameters:

Returns:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 572

def namespace(prefix)
  @namespaceCache ||= {}
  @namespaceUriCache ||= {}
  unless @namespaceCache.has_key?(prefix.to_s)
    @namespaceCache[prefix] = nil
    executeSQL("SELECT uri FROM #{namespace_binds} WHERE prefix=?", prefix.to_s) do |row|
      @namespaceCache[prefix.to_s] = Namespace.new(row[0], prefix.to_s)
      @namespaceUriCache[row[0].to_s] = prefix.to_s
    end
  end
  @namespaceCache[prefix.to_s]
end

#namespace_binds ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 638

def namespace_binds; "#{@internedId}_namespace_binds"; end

#normalizeTerm(term) ⇒ Object (protected)

T akes a term and ‘normalizes’ it. Literals are escaped, Graphs are replaced with just their identifiers



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 669

def normalizeTerm(term)
  case term
  when Graph    then normalizeTerm(term.identifier)
  when Literal  then term.to_s.rdf_escape
  when URIRef   then term.to_s.rdf_escape
  when BNode    then term.to_s
  else               term
  end
end

#nsbinding ⇒ Hash{String => Namespace}

Hash of prefix => Namespace bindings

Returns:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 604

def nsbinding
  unless @nsbinding.is_a?(Hash)
    @nsbinding = {}
    @uri_binding = {}
    executeSQL("SELECT prefix, uri FROM #{namespace_binds}") do |row|
      prefix, uri = row
      namespace = Namespace.new(uri, prefix)
      @nsbinding[prefix] = namespace
      # Over-write an empty prefix
      @uri_binding[uri] = namespace unless prefix.to_s.empty?
      @uri_binding[uri] ||= namespace
    end
    @nsbinding
  end
  @nsbinding
end

#prefix(namespace) ⇒ String

Prefix for namespace

Parameters:

Returns:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 588

def prefix(namespace)
  uri = namespace.is_a?(Namespace) ? namespace.uri.to_s : namespace

  @namespaceCache ||= {}
  @namespaceUriCache ||= {}
  unless @namespaceUriCache.has_key?(uri.to_s)
    @namespaceUriCache[uri.to_s] = nil
    executeSQL("SELECT prefix FROM #{namespace_binds} WHERE uri=?", uri) do |row|
      @namespaceUriCache[uri.to_s] = row[0]
    end
  end
  @namespaceUriCache[uri.to_s]
end

#queryAnalysis(query) ⇒ Object (protected)

Helper function for executing EXPLAIN on all dispatched SQL statements - for the pupose of analyzing index usage



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 835

def queryAnalysis(query)
end

#quoted_table ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 634

def quoted_table; "#{@internedId}_quoted_statements"; end

#remove(triple, context = nil)

This method returns an undefined value.

Remove a triple from the context and store

if subject, predicate and object are nil and context is not nil, the context is removed

Parameters:

  • triple (Triple)
  • context (Graph) (defaults to: nil) —

    (nil)



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 116

def remove(triple, context = nil)
  if context
    if triple.subject == nil && triple.predicate.nil? && triple.object.nil?
      return remove_context(context)
    end
  end
  
  if triple.predicate.nil? || triple.predicate != RDF_TYPE
    # Remove predicates other than rdf:type
    if !STRONGLY_TYPED_TERMS || triple.object.is_a?(Literal)
      clauseString, *params = self.buildClause(literal_table,triple,context)
      if !clauseString.empty?
        cmd = "DELETE FROM #{literal_table} #{clauseString}"
      else
        cmd = "DELETE FROM #{literal_table}"
      end
      executeSQL(_normalizeSQLCmd(cmd), params)
    end
    
    [quoted_table, asserted_table].each do |table|
      # If asserted non rdf:type table and obj is Literal, don't do anything (already taken care of)
      next if table == asserted_table && triple.object.is_a?(Literal)
      
      clauseString, *params = self.buildClause(table, triple, context)
      if !clauseString.empty?
        cmd = "DELETE FROM #{table} #{clauseString}"
      else
        cmd = "DELETE FROM #{table}"
      end
      executeSQL(_normalizeSQLCmd(cmd), params)
    end
  elsif triple.predicate == RDF_TYPE || triple.predicate.nil?
    # Need to check rdf:type and quoted partitions (in addition perhaps)
    clauseString, *params = self.buildClause(asserted_type_table,triple,context, true)
    if !clauseString.empty?
      cmd = "DELETE FROM #{asserted_type_table} #{clauseString}"
    else
      cmd = "DELETE FROM #{asserted_type_table}"
    end
    executeSQL(_normalizeSQLCmd(cmd), params)

    clauseString, *params = self.buildClause(quoted_table,triple,context)
    if !clauseString.empty?
      cmd = "DELETE FROM #{quoted_table} #{clauseString}"
    else
      cmd = "DELETE FROM #{quoted_table}"
    end
    executeSQL(_normalizeSQLCmd(cmd), params)
  end
end

#remove_context(identifier) ⇒ Object (protected) 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 640

def remove_context(identifier)
  executeSQL("SET AUTOCOMMIT=0") if @autocommit_default
  
  %w(quoted asserted type literal)
  [quoted_table,asserted_table,asserted_type_table,literal_table].each do |table|
    clauseString, *params = self.buildContextClause(identifier,table)
    executeSQL(
        _normalizeSQLCmd("DELETE from #{table} where #{clauseString}"),
        params
    )
  end
end

#rollback ⇒ Object 



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 631

def rollback; @db.rollback; end

#size(context = nil) ⇒ Integer

Number of statements in the store.

Parameters:

  • context (Graph) (defaults to: nil) —

    (nil)

Returns:

  • (Integer) 


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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 320

def size(context = nil)
  parameters = []
  quotedContext = assertedContext = typeContext = literalContext = nil

  clauseParts = self.buildContextClause(context,quoted_table)
  if clauseParts
    quotedContext = clauseParts.shift
    parameters += clauseParts
  end

  clauseParts = self.buildContextClause(context,asserted_table)
  if clauseParts
    assertedContext = clauseParts.shift
    parameters += clauseParts
  end

  clauseParts = self.buildContextClause(context,asserted_type_table)
  if clauseParts
    typeContext = clauseParts.shift
    parameters += clauseParts
  end

  clauseParts = self.buildContextClause(context,literal_table)
  if clauseParts
    literalContext = clauseParts.shift
    parameters += clauseParts
  end

  if context
    selects = [
      [
        asserted_type_table,
        'typeTable',
        typeContext ? 'where ' + typeContext : '',
        ASSERTED_TYPE_PARTITION
      ],
      [
        quoted_table,
        'quoted',
        quotedContext ? 'where ' + quotedContext : '',
        QUOTED_PARTITION
      ],
      [
        asserted_table,
        'asserted',
        assertedContext ? 'where ' + assertedContext : '',
        ASSERTED_NON_TYPE_PARTITION
      ],
      [
        literal_table,
        'literal',
        literalContext ? 'where ' + literalContext : '',
        ASSERTED_LITERAL_PARTITION
      ],
    ]
    q=unionSELECT(selects, :distinct => true, :select_type => COUNT_SELECT)
  else
    selects = [
      [
        asserted_type_table,
        'typeTable',
        typeContext ? 'where ' + typeContext : '',
        ASSERTED_TYPE_PARTITION
      ],
      [
        asserted_table,
        'asserted',
        assertedContext ? 'where ' + assertedContext : '',
        ASSERTED_NON_TYPE_PARTITION
      ],
      [
        literal_table,
        'literal',
        literalContext ? 'where ' + literalContext : '',
        ASSERTED_LITERAL_PARTITION
      ],
    ]
    q=unionSELECT(selects, :select_type => COUNT_SELECT)
  end

  count = 0
  executeSQL(self._normalizeSQLCmd(q), parameters) do |row|
    count += row[0].to_i
  end
  count
end

#transaction_aware? ⇒ true

Supports transactions

Returns:

  • (true) 


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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 65

def transaction_aware?; true; end

#triples(triple, context = nil) {|triple, context| ... } ⇒ Array<Triplle>

TODO:

These union all selects may be further optimized by joins

A generator over all the triples matching pattern.

quoted table

<id>_quoted_statements

asserted rdf:type table

<id>_type_statements

asserted non rdf:type table

<id>_asserted_statements

triple columns: subject,predicate,object,context,termComb,objLanguage,objDatatype class membership columns: member,klass,context termComb

Parameters:

  • triple (Triple)
  • context (Graph) (defaults to: nil) —

    (nil)

Yields:

  • (triple, context)

Yield Parameters:

Returns:

Raises:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 185

def triples(triple, context = nil)  # :yields: triple, context
  parameters = []
  
  if triple.predicate == RDF_TYPE
    # select from asserted rdf:type partition and quoted table (if a context is specified)
    clauseString, *params = self.buildClause('typeTable',triple,context, true)
    parameters += params
    selects = [
      [
        asserted_type_table,
        'typeTable',
        clauseString,
        ASSERTED_TYPE_PARTITION
      ],
    ]
  # elsif triple.predicate.is_a?(REGEXTerm) && triple.predicate.compiledExpr.match(RDF_TYPE) || triple.predicate.nil?
  elsif triple.predicate.nil?
    # Select from quoted partition (if context is specified), literal partition if (obj is Literal or None) and asserted non rdf:type partition (if obj is URIRef or None)
    selects = []
    if !STRONGLY_TYPED_TERMS || triple.object.is_a?(Literal) || triple.object.nil?
      clauseString, *params = self.buildClause('literal',triple,context)
      parameters += params
      selects += [
        [
          literal_table,
          'literal',
          clauseString,
          ASSERTED_LITERAL_PARTITION
        ]
      ]
    end
  
    if !triple.object.is_a?(Literal) || triple.object.nil?
      clauseString, *params = self.buildClause('asserted',triple,context)
      parameters += params
      selects += [
        [
          asserted_table,
          'asserted',
          clauseString,
          ASSERTED_NON_TYPE_PARTITION
        ]
      ]
    end

    clauseString, *params = self.buildClause('typeTable',Triple.new(triple.subject, RDF_TYPE, triple.object),context, true)
    parameters += params
    selects += [
      [
        asserted_type_table,
        'typeTable',
        clauseString,
        ASSERTED_TYPE_PARTITION
      ]
    ]
  elsif triple.predicate
    # select from asserted non rdf:type partition (optionally), quoted partition (if context is speciied), and literal partition (optionally)
    selects = []
    if !STRONGLY_TYPED_TERMS || triple.object.is_a?(Literal) || triple.object.nil?
      clauseString, *params = self.buildClause('literal',triple,context)
      parameters += params
      selects += [
        [
          literal_table,
          'literal',
          clauseString,
          ASSERTED_LITERAL_PARTITION
        ]
      ]
    end

    if !triple.object.is_a?(Literal) || triple.object.nil?
      clauseString, *params = self.buildClause('asserted',triple,context)
      parameters += params
      selects += [
        [
          asserted_table,
          'asserted',
          clauseString,
          ASSERTED_NON_TYPE_PARTITION
        ]
      ]
    end
  end
  
  if context
    clauseString, *params = self.buildClause('quoted',triple,context)
    parameters += params
    selects += [
      [
        quoted_table,
        'quoted',
        clauseString,
        QUOTED_PARTITION
      ]
    ]
  end
  
  q = _normalizeSQLCmd(unionSELECT(selects))
  results = []
  executeSQL(q, parameters) do |row|
    triple, graphKlass, idKlass, graphId = extractTriple(row, context)
    currentContext = graphKlass.new(:store => self, :identifier => idKlass.new(graphId))
    if block_given?
      yield(triple, currentContext)
    else
      results << triple
    end
  end
  
  results.uniq
end

#unionSELECT(selectComponents, options = {}) ⇒ Object (protected)

Helper function for building union all select statement

options[:distinct]

true or false

options[:select_type]

Defaults to TRIPLE_SELECT

Parameters:

  • select_components:: (Array) —

    list of [table_name, table_alias, table_type, where_clause]

  • options:: (Hash) —

    Options



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 843

def unionSELECT(selectComponents, options = {})
  selectType = options[:select_type] || TRIPLE_SELECT
  selects = []
  
  selectComponents.each do |sc|
    tableName, tableAlias, whereClause, tableType = sc

    case
    when selectType == COUNT_SELECT
      selectString = "select count(*)"
      tableSource = " from #{tableName} "
    when selectType == CONTEXT_SELECT
      selectString = "select #{tableAlias}.context, " + 
                            "#{tableAlias}.termComb as termComb "
      tableSource = " from #{tableName} as #{tableAlias} "
    when FULL_TRIPLE_PARTITIONS.include?(tableType)
      selectString = "select *"
      tableSource = " from #{tableName} as #{tableAlias} "
    when tableType == ASSERTED_TYPE_PARTITION
      selectString = "select #{tableAlias}.member as subject, " +
                            "\"#{RDF_TYPE}\" as predicate, " + 
                            "#{tableAlias}.klass as object, " + 
                            "#{tableAlias}.context as context, " + 
                            "#{tableAlias}.termComb as termComb, " + 
                            "NULL as objLanguage, " + 
                            "NULL as objDatatype"
      tableSource = " from #{tableName} as #{tableAlias} "
    when tableType == ASSERTED_NON_TYPE_PARTITION
      selectString = "select *, NULL as objLanguage, NULL as objDatatype"
      tableSource = " from #{tableName} as #{tableAlias} "
    else
      raise StoreException, "unionSELECT failed to find template: selectType = #{selectType}, tableType = #{tableType}"
    end
    
    selects << "#{selectString}#{tableSource}#{whereClause}"
  end
  
  orderStmt = selectType == TRIPLE_SELECT ? " order by subject, predicate, object" : ""
  
  selects.join(options[:distinct] ? " union all ": " union ") + orderStmt
end

#uri_binding ⇒ Hash{URIRef => Namespace}

Hash of uri => Namespace bindings

Returns:



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# File 'lib/rdf_context/store/abstract_sql_store.rb', line 623

def uri_binding
  nsbinding
  @uri_binding
end