X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fmathql%2Fhomepage%2Fwhatsnew.html;h=e00096b641cb838c1f80638ce34da99f12e6cc9b;hb=60c7321771851b82493bb202185ee184f1e7a3d1;hp=72b12ff7cc7dfb1e17777a1143e0b7d0e93b6903;hpb=5f240d0c42f1729689be272852083ecfb297a8e1;p=helm.git diff --git a/helm/mathql/homepage/whatsnew.html b/helm/mathql/homepage/whatsnew.html index 72b12ff7c..e00096b64 100644 --- a/helm/mathql/homepage/whatsnew.html +++ b/helm/mathql/homepage/whatsnew.html @@ -3,139 +3,267 @@ MathQL - + - + - + - +

MathQL-1

- +

A query language for RDF metadata

- + - - - + + - + - - - + + +
+
+
+

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 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:
+ + + +
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
+
+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;
+
+ +
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;
+
+ +
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";
+
+ +
same as the previous but tells that this is a default  correspondence; +
+
+ +
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;
+
+ +
a line like this must end the map file. 
+
+Here you can find the current +version of PostgreSQL database map for HELM.
+
+ How does the interpreter use the map? The map file is read during +the interpreter initialization process from the file pointed by the MATHQL_DB_MAP +environment variable and is used during the execution of each property +operation in the issued queries.When executing a property operation, +the interpreter uses the map to find the smallest set of database tables +containing the information required by the given access paths and then queries +these tables to obtain the wanted information.
+ + + +
- +
+ - + + - +
    -
  • What's new
    -
    • - +
  • What's new
    +
    • + +
- + + - + - + - + -
- 		- +
+ 		+
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>
-
- 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:
    • - -
- + +
<query> := "add" [ "distr" ]? [ <groups> | +<avar> ] "in" <query>
+ <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 mathing 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.
    -
    • - + 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.
      • +
    -
-
-
+