Thread: Re: PL/PgSQL discussion
jwieck@debis.com (Jan Wieck) wrote: > But I would like to have some discussion on language itself. > So I wrote down what I had in mind. The document is appended > below. > > Please comment/suggest ! > > Someone gave a hint about global variables existing during a > session. What is a session than? One transaction? The > backends lifetime? I think it is a time from connect to disconnect, which currently equals to backends lifetime, but may in future be shorter, if we will implement a backend pool for quick-starting servers. > And should global variables be visible by > more than one function? How are they global then ? I think that global variables are something like DateStyle is now. > I vote for NO! In that case we need > something like packages of functions that share globals. Or we need local temporary tables. > PL/pgSQL > A procedural language for the PostgreSQL RDBMS > 1st draft > > Jan Wieck <jwieck@debis.com> > > Notice > > This document is for the postgresql-hackers community for > completing the syntax specification of PL/pgSQL. The > extension module described here doesn't exist up to now! > > Preface > > PL/pgSQL is a procedural language based on SQL designed for > the PostgreSQL database system. > > The extensibility features of PostgreSQL are mostly based on > the ability to define functions for various operations. > Functions could have been written in PostgreSQL's SQL dialect > or in the C programming language. Functions written in C are > compiled into a shared object and loaded by the database > backend process on demand. Also the trigger features of > PostgreSQL are based on functions but required the use of the > C language. > > Since version 6.3 PostgreSQL supports the definition of > procedural languages. In the case of a function or trigger > procedure defined in a procedural language, the database has > no builtin knowlege how to interpret the functions source > text. Instead, the function and trigger calls are passed into > a handler that knows the details of the language. The > handler itself is function compiled into a shared object and > loaded on demand. > > Overview > > The PL/pgSQL language is case insensitive. All keywords and > identifiers can be used in upper-/lowercase mixed. > > PL/pgSQL is a block oriented language. A block is defined as > > [<<label>>] > [DECLARE > -- declarations] > BEGIN > -- statements > END; > > > There can be any number of subblocks in the statements > section of a block. Subblocks can be used to hide variables > from outside a block of statements (see Scope and visability > below). I think that subblock should also be used as the extent of IF, FOR ... LOOP, WHILE and other such statements. Then we would not need the END IF, END LOOP etc. > > > Comments > > There are two types of comments in PL/pgSQL. A double dash > '--' starts a comment that extends to the end of the line. A > '/*' starts a block comment that extends to the next '*/'. > Block comments cannot be nested, but double dash comments can > be enclosed into a block comment. And vice versa : block comment delimiters can be commented out by -- > > > Declarations > > All variables, rows and records used in a block or it's > subblocks must be declared in the declarations section of the > block. The parameters given to the function are > automatically declared with the usual identifiers $n. How hard would it bet to have named parameters, or why must we use alias? > The declarations have the following syntax: > > <name> [CONSTANT] <type> [NOT NULL] > [DEFAULT | := <value>]; > > Declares a variable of the specified type. If the > variable is declared as CONSTANT, the value cannot be > changed. If NOT NULL is specified, an assignment of a > NULL value results in a runtime error. Since the > default value of a variable is the SQL NULL value, > all variables declared as NOT NULL must also have a > default value. > > The default value is evaluated at the actual function > call. So assigning 'now' to an abstime varable causes > the variable to have the time of the actual function > call, not when the function was compiled. > > <name> <class>%ROWTYPE; > > Declares a row with the structure of the given class. > Class must be an existing table- or viewname of the > database. The fields of the row are accessed in the > dot notation. Parameters to a procedure could be > tuple types. In that case the corresponding > identifier $n will be a rowtype. Only the user > attributes and the oid of a tuple are accessible in > the row. There must be no whitespaces between the > classname, the percent and the ROWTYPE keyword. > > <name> RECORD; > > Records are similar to rowtypes, but they have no > predefined structure and it's impossible to assign a > value into them. They are used in selections and FOR > loops to hold one actual database tuple from a select > operation. One and the same record can be used in > different selections (but not in nested ones). > > <name> ALIAS FOR $n; > > For better readability of the code it's possible to > define an alias for a positional parameter to the > function. > > Datatypes > > The type of a variable can be any of the existing data types > of the database. <type> above is defined as: > > postgesql-basetype > or variable%TYPE > or rowtype.field%TYPE > or class.field%TYPE > > As for the rowtype declaration, there must be no whitespaces > between the classname, the percent and the TYPE keyword. > > Expressions > > All expressions used in PL/pgSQL statements are processed > using the backends executor. Since even a constant looking > expression can have a totally different meaning for a > particular data type (as 'now' for abstime), it is impossible > for the PL/pgSQL parser to identify real constant values > other than the NULL keyword. The expressions are evaluated by > internally executing a query > > SELECT <expr> > > over the SPI manager. In the expression, occurences of > variable identifiers are substituted by parameters and the > actual values from the variables are passed to the executor > as query parameters. All the expressions used in a PL/pgSQL > function are only prepared and saved once. > > Statements > > Anything not understood by the parser as specified below will > be put into a query and sent down to the database engine to > execute. The resulting query should not return any data. > > Assignment > > An assignment of a value to a variable or rowtype field > is written as: > > <identifier> := <expr>; > > If the expressions result data type doesn't match the > variables data type, or the variables atttypmod value is > known (as for char(20)), the result value will be > implicitly casted by the PL/pgSQL executor using the > result types output- and the variables type input- > functions. Note that this could potentially result in > runtime errors generated by the types input functions. > > An assignment of a complete selection into a record or > rowtype can be done as: > > SELECT targetlist INTO <recname|rowname> FROM fromlist; > > If a rowtype is used as target, the selected targetlist > must exactly match the structure of the rowtype or a > runtime error occurs. The fromlist can be followed by > any valid qualification, grouping, sorting etc. There is > a special condition [NOT] FOUND that can be used > immediately after a SELECT INTO to check if the data has > been found. > > SELECT * INTO myrec FROM EMP WHERE empname = myname; > IF NOT FOUND THEN > ELOG ERROR 'employee %s not found' myname; > END IF; > > In addition, the select statement must not return more > that one row. If multiple rows are returned, a runtime > error will be generated. > > Returning from the function > > RETURN <expr>; > > The function terminates and the value of <expr> will be > returned to the upper executor. The return value of a > function cannot be undefined. If control reaches the end > of the toplevel block of the function without hitting a > RETURN statement, a runtime error will occur. What can <expr> be? Possibilities: null, single value, record, recordset AFAIK, recordsets are usually returned by more strange constructs, like haveing some kinds of breakpoints inside the loop that either returns a record or some EOF token. > A conditional loop that is executed as long as the > evaluation of <expr> returns true. > > [<<label>>] > FOR <name> IN [REVERSE] <expr>..<expr> LOOP > -- statements > END LOOP. Perhaps PL/PgSQL should have some notation for specifying immediate lists of other kinds of values as well,perhaps like ['aa','bb','cc'], so that one cold loop over not only integers. Perhaps even with type specifiers, like [::time '22.01', '13.47.05', '15.20'] > > > A loop that iterates over a range of integer values. The > variable <name> is automatically created as type integer > and exists only inside the loop. The two expressions > giving the lower and upper bound of the range are > evaluated only when entering the loop. The iteration step > is 1. > > FOR <recname|rowname> IN <select_clause> LOOP > -- statements > END LOOP; > > The record or row is assigned all the rows resulting from > the select clause and the statements executed for each. > If the loop is terminated with an EXIT statement, the > last accessed row is still accessible in the record or > rowtype. > > EXIT [label] [WHEN <expr>]; > > If no label given, the innermost loop is terminated and > the statement following END LOOP is executed next. If > label is given, it must be the label of the current or an > upper level of nested loops or blocks. Then the named > loop or block is terminated and control continues with > the statement after the loops/blocks corresponding END. > Keep up the nice work! Hannu
Hannu Krosing wrote:
>
> jwieck@debis.com (Jan Wieck) wrote:
>
> > Someone gave a hint about global variables existing during a
> > session. What is a session than? One transaction? The
> > backends lifetime?
>
> I think it is a time from connect to disconnect, which currently equals to backends
> lifetime, but may in future be shorter, if we will implement a backend pool for
> quick-starting servers.
Hmmm - how does a language handler then notice that a new
session began?
> >
> > PL/pgSQL is a block oriented language. A block is defined as
> >
> > [<<label>>]
> > [DECLARE
> > -- declarations]
> > BEGIN
> > -- statements
> > END;
>
>
>
> >
> >
> > There can be any number of subblocks in the statements
> > section of a block. Subblocks can be used to hide variables
> > from outside a block of statements (see Scope and visability
> > below).
>
> I think that subblock should also be used as the extent of IF, FOR ... LOOP, WHILE and
> other such statements.
>
> Then we would not need the END IF, END LOOP etc.
The LOOP ... END LOOP etc. syntax is just what I saw in
Oracles PL/SQL documentation. I could also live with
BEGIN...END, but what is it good for to be different?
>
> >
> >
> > Comments
> >
> > There are two types of comments in PL/pgSQL. A double dash
> > '--' starts a comment that extends to the end of the line. A
> > '/*' starts a block comment that extends to the next '*/'.
> > Block comments cannot be nested, but double dash comments can
> > be enclosed into a block comment.
>
> And vice versa : block comment delimiters can be commented out by --
Right - works already :-)
>
> >
> >
> > Declarations
> >
> > All variables, rows and records used in a block or it's
> > subblocks must be declared in the declarations section of the
> > block. The parameters given to the function are
> > automatically declared with the usual identifiers $n.
>
> How hard would it bet to have named parameters, or why must we use alias?
That isn't subject to the PL handler. All the PL handler
knows about the function is in pg_proc and pg_type. There are
no parameter names, and that's what the ALIAS idea came from.
If we sometimes implement a new function call interface, this
might be possible. Some details about what I have in mind:
Add a field to pg_proc that tells the backend the call
interface the function uses.
Create a new catalog pg_parameter, that holds the
parameter names and other information (like notnull,
atttypmod etc.). So a function can be defined to expect a
VARCHAR(20) NOT NULL.
The new call interface then hands out more information to
the function than now. It's the functions Oid, the
parameter Datums, a character array telling which of the
Datums are NULL and the usual bool pointer where the
function can tell that it's return value is NULL.
> > Returning from the function
> >
> > RETURN <expr>;
> >
> > The function terminates and the value of <expr> will be
> > returned to the upper executor. The return value of a
> > function cannot be undefined. If control reaches the end
> > of the toplevel block of the function without hitting a
> > RETURN statement, a runtime error will occur.
>
> What can <expr> be?
>
> Possibilities: null, single value, record, recordset
>
> AFAIK, recordsets are usually returned by more strange constructs, like haveing some
> kinds of breakpoints inside the loop that either returns a record or some EOF token.
>
Currently only 'null' and 'single value'. The executor
doesn't accept anything else for non-sql language functions.
PL functions are treated by the executor like 'C' functions.
> > A conditional loop that is executed as long as the
> > evaluation of <expr> returns true.
> >
> > [<<label>>]
> > FOR <name> IN [REVERSE] <expr>..<expr> LOOP
> > -- statements
>
> > END LOOP.
>
> Perhaps PL/PgSQL should have some notation for specifying immediate lists of other kinds
> of values as well,perhaps like ['aa','bb','cc'], so that one cold loop over not only
> integers. Perhaps even with type specifiers, like [::time '22.01', '13.47.05', '15.20']
Good issue. Could be done.
>
> Keep up the nice work!
>
> Hannu
>
>
Already reached the point of no return. The first tiny
function ran without problems:
CREATE FUNCTION f1(int4, int4) RETURNS int4 AS '
BEGIN
RETURN $1 + $2;
END;
' LANGUAGE 'plpgsql';
I set up a little test table with 2 int4 fields containing
some thousand records. Then I wrote equivalent functions in
'sql', 'plpgsql' and 'pltcl'. The execution times for a
query
SELECT sum(func(a, b)) FROM t1;
are:
Builtin SQL language 100%
PL/Tcl 180%
PL/pgSQL 230%
PL/Tcl is slower than builtin SQL because the internals of it
require the two parameters to be converted to their external
representation, than calling the Tcl interpreter who parses
them back to numbers, calculates the result, returns it as
string and then it's parsed back to int4 internal value.
In the PL/pgSQL case I haven't expected that big performance
loss. The calculation is internally done with a saved query
plan (made on the first call) that does a
SELECT $1 + $2
with two int4 parameters. This is exactly what the SQL
version of the above does! And >95% of the execution time
for the function call are spent in SPI_execp(). Since
SPI_execp() calls ExecutorRun() directly, I think the
querydesc creation and/or plan copying on each invocation is
the time consuming part. I assume that there are some
optimizable corners in SPI where we can gain more speed. So I
continue with PL/pgSQL as it is now and speed it up later by
tuning SPI.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck@debis.com (Jan Wieck) #
Jan Wieck wrote: > Hannu Krosing wrote: > > > > jwieck@debis.com (Jan Wieck) wrote: > > > > > Someone gave a hint about global variables existing during a > > > session. What is a session than? One transaction? The > > > backends lifetime? > > > > I think it is a time from connect to disconnect, which currently equals to backends > > lifetime, but may in future be shorter, if we will implement a backend pool for > > quick-starting servers. > > Hmmm - how does a language handler then notice that a new > session began? Probably by defining the reset_session or init_session functions for the language handler and calling it at the connect time. > > > > > > PL/pgSQL is a block oriented language. A block is defined as > > > > > > [<<label>>] > > > [DECLARE > > > -- declarations] > > > BEGIN > > > -- statements > > > END; > > > > > > > > > > > > > > > There can be any number of subblocks in the statements > > > section of a block. Subblocks can be used to hide variables > > > from outside a block of statements (see Scope and visability > > > below). > > > > I think that subblock should also be used as the extent of IF, FOR ... LOOP, WHILE and > > other such statements. > > > > Then we would not need the END IF, END LOOP etc. > > The LOOP ... END LOOP etc. syntax is just what I saw in > Oracles PL/SQL documentation. I could also live with > BEGIN...END, but what is it good for to be different? then again we don't need the block delimiters ;) > > > > > > Declarations > > > > > > All variables, rows and records used in a block or it's > > > subblocks must be declared in the declarations section of the > > > block. The parameters given to the function are > > > automatically declared with the usual identifiers $n. > > > > How hard would it bet to have named parameters, or why must we use alias? > > That isn't subject to the PL handler. All the PL handler > knows about the function is in pg_proc and pg_type. There are > no parameter names, and that's what the ALIAS idea came from. I just meant them as an automatic way to declare and use aliases for $N, like for example C does currently. The calling function does not know the local names of called function in C either. > If we sometimes implement a new function call interface, this > might be possible. Some details about what I have in mind: > > Add a field to pg_proc that tells the backend the call > interface the function uses. > > Create a new catalog pg_parameter, that holds the > parameter names and other information (like notnull, > atttypmod etc.). So a function can be defined to expect a > VARCHAR(20) NOT NULL. This again can be done by automatically rewriting these to additional statements to check for this as first things in the function body. It makes only a theoretical difference if the error is reportid before the call or just after it. > Currently only 'null' and 'single value'. The executor > doesn't accept anything else for non-sql language functions. > PL functions are treated by the executor like 'C' functions. Actually what I understood from the docs was thatit is 'terribly complicated' and 'beyond the scope of this tutorial', but not impossible ;) --------- Hannu
Hannu Krosing wrote:
>
> Jan Wieck wrote:
>
> > Hannu Krosing wrote:
> > >
> > > jwieck@debis.com (Jan Wieck) wrote:
> > >
> >
> > Hmmm - how does a language handler then notice that a new
> > session began?
>
> Probably by defining the reset_session or init_session functions for the language handler and
> calling it at the connect time.
Not in the current implementation of the backend/pl_handler
interface. But a global variable SessionId might help.
> > > Then we would not need the END IF, END LOOP etc.
> >
> > The LOOP ... END LOOP etc. syntax is just what I saw in
> > Oracles PL/SQL documentation. I could also live with
> > BEGIN...END, but what is it good for to be different?
>
> then again we don't need the block delimiters ;)
Forgotten in the 1st draft. Variables are initialized to
their default values every time a block/subblock is entered.
Not only when the function is entered.
...
FOR i IN 1..10 LOOP
DECLARE
flag bool DEFAULT false;
n integer DEFAULT 0;
BEGIN
...
END;
END LOOP;
...
> > Create a new catalog pg_parameter, that holds the
> > parameter names and other information (like notnull,
> > atttypmod etc.). So a function can be defined to expect a
> > VARCHAR(20) NOT NULL.
>
> This again can be done by automatically rewriting these to additional statements to check for
> this as first things in the function body. It makes only a theoretical difference if the error
> is reportid before the call or just after it.
But this rewriting must be done when the function is created.
At this time, the pl_handler and it's parser aren't called.
It is done by the backends main parser. For loadable
procedural languages, the main parser doesn't know anything
about the languages syntax or if the string given after AS is
a program text at all. It only creates the pg_proc tuple.
>
> > Currently only 'null' and 'single value'. The executor
> > doesn't accept anything else for non-sql language functions.
> > PL functions are treated by the executor like 'C' functions.
>
> Actually what I understood from the docs was thatit is 'terribly complicated' and 'beyond the
> scope of this tutorial', but not impossible ;)
I tried that really hard with no luck. And I know
ExecMakeFunctionResult() pretty good. But I'll give it
another shot when PL/pgSQL reached a state where it makes
sense.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck@debis.com (Jan Wieck) #
Jan Wieck wrote: > > > Hmmm - how does a language handler then notice that a new > > > session began? > > > > Probably by defining the reset_session or init_session functions for the language handler and > > calling it at the connect time. > > Not in the current implementation of the backend/pl_handler > interface. But a global variable SessionId might help. Neither do we have backend pooling now. > > > > Then we would not need the END IF, END LOOP etc. > > > > > > The LOOP ... END LOOP etc. syntax is just what I saw in > > > Oracles PL/SQL documentation. I could also live with > > > BEGIN...END, but what is it good for to be different? > > > > then again we don't need the block delimiters ;) > > Forgotten in the 1st draft. Variables are initialized to > their default values every time a block/subblock is entered. > Not only when the function is entered. > > ... > FOR i IN 1..10 LOOP > DECLARE > flag bool DEFAULT false; > n integer DEFAULT 0; > BEGIN > ... > END; > END LOOP; > ... Ok, this makes sense. > > This again can be done by automatically rewriting these to additional statements to check for > > this as first things in the function body. It makes only a theoretical difference if the error > > is reportid before the call or just after it. > > But this rewriting must be done when the function is created. > At this time, the pl_handler and it's parser aren't called. Ok, I understand it now. <name> ALIAS FOR $n; is to overcome the split between the two parser. > It is done by the backends main parser. For loadable > procedural languages, the main parser doesn't know anything > about the languages syntax or if the string given after AS is > a program text at all. It only creates the pg_proc tuple. And another thing: Does'nt the Oracle PL/SQL have both input and input/output parameters ? It's more than a year since i last used it but I think that this is the case. Hannu
> > jwieck@debis.com (Jan Wieck) wrote: > > > But I would like to have some discussion on language itself. > > So I wrote down what I had in mind. The document is appended > > below. > > > > Please comment/suggest ! A question. Will it be possible to call functions from the PL/pgSQL? This covers a fair bit, for example to evaluate expressions and casts etc as well as calling user functions. Or was this covered and I just missed it somehow? -dg David Gould dg@illustra.com 510.628.3783 or 510.305.9468 Informix Software (No, really) 300 Lakeside Drive Oakland, CA 94612 - I realize now that irony has no place in business communications.
jwieck@debis.com (Jan Wieck) wrote:
> Hannu Krosing wrote:
> > jwieck@debis.com (Jan Wieck) wrote:
...
> > I think it is a time from connect to disconnect, which currently equals to backends
> > lifetime, but may in future be shorter, if we will implement a backend pool for
> > quick-starting servers.
>
> Hmmm - how does a language handler then notice that a new
> session began?
Either when the backend exits, or is re-initted to go back to the idle pool.
> > > PL/pgSQL is a block oriented language. A block is defined as
> > > [<<label>>]
> > > [DECLARE
> > > -- declarations]
> > > BEGIN
> > > -- statements
> > > END;
...
> > I think that subblock should also be used as the extent of IF, FOR ... LOOP, WHILE and
> > other such statements.
> > Then we would not need the END IF, END LOOP etc.
>
> The LOOP ... END LOOP etc. syntax is just what I saw in
> Oracles PL/SQL documentation. I could also live with
> BEGIN...END, but what is it good for to be different?
I am not convinced that imitating Oracle is necessarily the best possible way
to proceed. If there is a standard, and I think there is at least a proposal
(called PSM, if memory serves), we might (but only might) want to do that.
Otherwise, either lets steal something worth stealing or invent something
better than whats out there.
> > How hard would it bet to have named parameters, or why must we use alias?
>
> That isn't subject to the PL handler. All the PL handler
> knows about the function is in pg_proc and pg_type. There are
> no parameter names, and that's what the ALIAS idea came from.
...
> > > Returning from the function
> > >
> > > RETURN <expr>;
> > >
> > What can <expr> be?
> >
> > Possibilities: null, single value, record, recordset
> >
> > AFAIK, recordsets are usually returned by more strange constructs, like haveing some
> > kinds of breakpoints inside the loop that either returns a record or some EOF token.
> >
> Currently only 'null' and 'single value'. The executor
> doesn't accept anything else for non-sql language functions.
> PL functions are treated by the executor like 'C' functions.
This limitation suggests that PL/pgSQL functions want to _be_ SQL functions,
not 'C' functions. Handy to be able to write:
begin
if $1 = "totals" then
select sum(qty), sum(qty) * price from sales_orders where ...;
else if $1 = "details"
select qty, price from sales_orders where ...
Ok, lousy example, but I have seen this kind of thing in apps ...
> Already reached the point of no return. The first tiny
> function ran without problems:
I am impressed.
> CREATE FUNCTION f1(int4, int4) RETURNS int4 AS '
> BEGIN
> RETURN $1 + $2;
> END;
> ' LANGUAGE 'plpgsql';
>
> I set up a little test table with 2 int4 fields containing
> some thousand records. Then I wrote equivalent functions in
> 'sql', 'plpgsql' and 'pltcl'. The execution times for a
> query
>
> SELECT sum(func(a, b)) FROM t1;
>
> are:
>
> Builtin SQL language 100%
> PL/Tcl 180%
> PL/pgSQL 230%
>
> PL/Tcl is slower than builtin SQL because the internals of it
> require the two parameters to be converted to their external
> representation, than calling the Tcl interpreter who parses
> them back to numbers, calculates the result, returns it as
> string and then it's parsed back to int4 internal value.
>
> In the PL/pgSQL case I haven't expected that big performance
> loss. The calculation is internally done with a saved query
> plan (made on the first call) that does a
>
> SELECT $1 + $2
>
> with two int4 parameters. This is exactly what the SQL
> version of the above does! And >95% of the execution time
> for the function call are spent in SPI_execp(). Since
> SPI_execp() calls ExecutorRun() directly, I think the
> querydesc creation and/or plan copying on each invocation is
> the time consuming part. I assume that there are some
> optimizable corners in SPI where we can gain more speed. So I
> continue with PL/pgSQL as it is now and speed it up later by
> tuning SPI.
I think you might want to do some profiling to find where the time is
really going. Not to throw water on your parade, but being slower than
tcl is something of an achievement ;-).
I wish I could be of more use than this, but that will have to wait
until I get some time to look over the postgres code a bit. It is similar
to Illustra in many ways, but the two lines branched apart quite a while
ago and have gone in different directions especially in the language areas.
David Gould dg@illustra.com 510.628.3783 or 510.305.9468
Informix Software (No, really) 300 Lakeside Drive Oakland, CA 94612
- I realize now that irony has no place in business communications.
Hannu Krosing wrote:
>
> And another thing:
>
> Does'nt the Oracle PL/SQL have both input and input/output parameters ?
>
> It's more than a year since i last used it but I think that this is the case.
Right, they have. But PostgreSQL doesn't and so PL/pgSQL
can't. PL/pgSQL cannot do any thing that a C function in
PostgreSQL cannot do. The PL handler is written in C and that
is what the executor calls instead of the compiled function.
From the backends point of view, a PL handler is just one C
function with a bunch of personalities.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck@debis.com (Jan Wieck) #
David Gould wrote:
>
> >
> > jwieck@debis.com (Jan Wieck) wrote:
> >
> > > But I would like to have some discussion on language itself.
> > > So I wrote down what I had in mind. The document is appended
> > > below.
> > >
> > > Please comment/suggest !
>
> A question. Will it be possible to call functions from the PL/pgSQL? This
> covers a fair bit, for example to evaluate expressions and casts etc as
> well as calling user functions.
>
> Or was this covered and I just missed it somehow?
It is covered automagically by the way I'm implementing the
assignement. The assign code internally does a SELECT. And
thus:
n := count(*) from t1;
works (even if it's far from standard I think).
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck@debis.com (Jan Wieck) #