+
+
-
-
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+
- - What's new
-
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+ - What's new
+
+
+
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- |
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+ |
+
+
What's new
-
-
- This page reports the newly implemented
-features of MathQL-1 that are not included in the ufficial
+
+ This page reports the newly implemented
+ features of MathQL-1 that are not included in the official documentation yet.
-
-Changes and additions to MathQL-1 operators:
+
+
+
+ Changes and additions to MathQL-1 operators:
+
+
- - The add operator now accepts a syntax extension allowing
-to specify more than one explicit attribute group.
+ - The add operator now accepts a syntax extension allowing
+ to specify more than one explicit attribute group.
+
+
The syntax now is:
+
<query> := "add" [ "distr" ]? [ <groups> |
<avar> ] "in" <query>
-<groups> := <group> [ ";" <group> ]*
-<group> := <attribute> [ "," <attribute> ]*
-<attribute> := <value> "as" <path>
+ <groups> := <group> [ ";" <group> ]*
+ <group> := <attribute> [ "," <attribute> ]*
+ <attribute> := <value> "as" <path>
+
+ Examples:
+ the query add "1" as "a", "2" as "b" in subj "A" gives the result
+ "A" attr {"a"="1"; "b"="2"} while
+ the query add "1" as "a"; "2" as "b" in subj "A" gives the result
+ "A" attr {"a"="1"}, {"b"="2"}.
+
+
+
+ - The new align operator takes an integer i (represented
+ as a string), a multiple string value v and returns the same v
+ where each string with length n < i is prefixed with i - n
+ spaces. The syntax of the add operator is:
+
+
+
+ <value> := "align" <string> "in" <value>
+
+ This operators aligns strings containing numbers so that their alphabetic
+ order agrees with their numeric order.
+
+
+
+ - The intersect operator now intersects the attribute
+groups of the matching subject strings set-theoretically rather than making
+their "Cartesian product". This semantics reduces the computational costs
+and makes intersection the dual of union.
+
+
+
+
+ - The property operator now accepts more than one isfalse
+ clause to increase the complexity of the constraint condition used to filter
+ the raw query results. This feature is exploited in the queries produced
+by the HELM query generator.
+
+
+
+
+
+ The PostgreSQL database map:
+
+The PostgreSQL database map is a file describing how the MathQL-1
+interpreter must interact with the underlying PostgreSQL database, when it
+is run in Postgres mode. Currently this file contains the following information:
+
+ - the database connection string to be used when the interpreter
+opens a connection with the database;
+
+
+ - the map describing the correspondence between the metadata
+access paths used by the property operator and the fields of the database
+tables.
+
+The format of the file is textual and line oriented, but a corresponding
+XML syntax will be provided soon.
+The first line must contain the database connection string and the subsequent
+lines contain the map with the following syntax:
+
+ - blank lines: ignored (used for separation);
+
+
+ - lines starting with a # followed by a space: ignored (used for
+comments);
+
+
+
+ - <table_name> <field_name> "<-"
+[ <path_component> ]*
+
+
+ the information about the metadata denoted by the given
+path is found in the given field of the given table in the database. For
+example the line:
+
+refobj h_occurrence <- refObj h:occurrence
-Examples:
-the query add "1" as "a", "2" as "b" in subj "A" gives the result
- "A" attr {"a"="1"; "b"="2"} while
-the query add "1" as "a"; "2" as "b" in subj "A" gives the result
- "A" attr {"a"="1"}, {"b"="2"}.
+tells that the metadata denoted by the path /"refObj"/"h:occurrence"
+is found in the field "h_occurrence" of the table "refobj" in the database,
+while:
+
+refobj source <-
+
+tells that the metadata denoted by the path / is found in the field
+"source" of the table "refobj" in the database;
- - The new align operator takes an integer i (represented
-as a string), a multiple string value v and returns the same v
-where each string with length n < i is prefixed with i - n
-spaces. The syntax of the add operator is:
+ - <table_name> <field_name> "<+"
+[ <path_component> ]*
+
- <value> := "align" <string> "in" <value>
+ same as the previous but defines a default table and field
+for the given path. This is used to force the interpreter to query a particular
+table when the information denoted by a path can be found in more than one
+table and field. For example:
+
+objectname source <+
+refobj source <-
+refrel source <-
+refsort source <-
+
+tells that the metadata denoted by the path / is found in the "source"
+field of the "objectname", "refobj", "refrel" and "refsort" tables, and that
+the first choice is preferred;
+
+
+ - <table_name> "<-" [ <path_component> ]*
+
+ the given path denotes a structured metadata whose components
+are found in the fields of the given table. For example:
+
+refobj <- refObj
+
+tells that the path /"refObj" denotes a structured metadata whose
+components are found in the fields of the table "refobj";
+
+
+ - <table_name> "<+" [ <path_component> ]*
+
+ same as the previous but tells that this is a default correspondence;
-This operators aligns strings containing numbers so that their alphabetic
-order agrees with their numeric order.
-
- - The intersect operator now intersects the attribute groups
-of the mathing subject strings set-theoretically rather than making their
-"Cartesian product". This semantics reduces the computational costs and makes
-intersection the dual of union.
+ - <virtual_table_name> "->" <concrete_table_name>
+ defines a correspondence between a virtual table name an
+a concrete table name. All the <table_name> entries represent virtual
+table names that are mapped to concrete table names using the identity function
+unless a particular mapping is defined for them using the above construction.
+This mechanism allows to define several set of metadata on the same database
+table as in:
+
+refobj source
+ <-
+refobj h_occurrence <-
+ refObj h:occurrence
+backpointer source
+ <- backPointer h:occurrence
+backpointer h_occurrence <-
+backpointer
+ -> refobj
+
+ which defines four path accessing two virtual tables ("refobj"
+and "backpointer") and then maps these tables in a single concrete table;
+
- - The property operator now accepts more than one isfalse
-clause to increase the complexity of the constraint condition used to filter
-the query results. This feature is exploited in the queries produced by the
- HELM query generator.
+ - "->"
- |
-
-
-