Thread: clone_schema function

 

 

From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Melvin Davidson
Sent: Wednesday, September 09, 2015 12:31 PM
To: pgsql-general@postgresql.org
Subject: [GENERAL] clone_schema function

 

I noted there was an inquiry as to how to copy or clone_schema
an entire schema. The standard method for doing that is to
1. pg_dump the schema in plain format
2. edit the dump file and change all occurrences of the schema name
3. reload the dump into the new schema.

The attached function is an alternate method for doing that.
It is a revision of the clone_schema by by Emanuel '3manuek'
from https://wiki.postgresql.org/wiki/Clone_schema

Originally, it did not copy views, functions or data from
the source schema despite the claim that it "copies everything".

I've added error checking and verified that it now copies the
current sequnce values, table data, views and functions.

As always, use with caution.
--

Melvin Davidson

 

I assume you are aware that this script does not produce complete copy of the source schema.

Foregn Key constraints are not recreated along with the tables.

 

Regards,

Igor Neyman

 

 

 

 

From: Melvin Davidson [mailto:melvin6925@gmail.com]
Sent: Wednesday, September 09, 2015 4:48 PM
To: Igor Neyman <ineyman@perceptron.com>
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] clone_schema function

 

Thanks Igor,

hmm, apparently the "INCLUDING CONSTRAINTS' option of "CREATE TABLE' has a glitch and only includes the primary key.

I also noticed that INCLUDING ALL generates an error, so I'll have to report that also.

I'll go eat some crow and work on a fix to add all constraints in the meantime.

 

 

It’s not a bug.

According to docs:

“Not-null constraints are always copied to the new table. CHECK constraints will only be copied if INCLUDING CONSTRAINTS is specified; other types of constraints will never be copied.”

So, FK constraints are not supposed to be copied.

 

Regards,

Igor Neyman

Yes, however, the documentation would be a lot clearer if it said "copies all constraints except foreign keys". I've made this known.

At any rate, I've attached a new version of the function that now does copy the foreign keys. Let me know if I missed anything else.

On Thu, Sep 10, 2015 at 9:09 AM, Igor Neyman <ineyman@perceptron.com> wrote:

 

 

From: Melvin Davidson [mailto:melvin6925@gmail.com]
Sent: Wednesday, September 09, 2015 4:48 PM
To: Igor Neyman <ineyman@perceptron.com>
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] clone_schema function

 

Thanks Igor,

hmm, apparently the "INCLUDING CONSTRAINTS' option of "CREATE TABLE' has a glitch and only includes the primary key.

I also noticed that INCLUDING ALL generates an error, so I'll have to report that also.

I'll go eat some crow and work on a fix to add all constraints in the meantime.

 

 

It’s not a bug.

According to docs:

“Not-null constraints are always copied to the new table. CHECK constraints will only be copied if INCLUDING CONSTRAINTS is specified; other types of constraints will never be copied.”

So, FK constraints are not supposed to be copied.

 

Regards,

Igor Neyman

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

Melvin Davidson wrote:
> Alvaro,
>
> no I haven't updated the wiki (or git). To be honest, I'm retired and I
> just don't want to bother learning something new,
> but I do enjoy helping othersfrom time to time. I would consider it a favor
> if you would do the update for me.

I wouldn't want to prevent your enjoyment of learning something new such
as editing the wiki -- in spite of which I added a link to the wiki.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

        Melvin Davidson wrote:

> I've added error checking and verified that it now copies the
> current sequnce values, table data, views and functions.

The code dealing with functions is seriously flawed.

Consider that part:
     SELECT pg_get_functiondef(func_oid) INTO qry;
     SELECT replace(qry, source_schema, dest_schema) INTO dest_qry;
     EXECUTE dest_qry;

It suggests that to duplicate a function in schema A to B,
every letter A in the entire function definition should be replaced
by B, garbling everything along the way.
For example CREATE FUNCTION would become CREBTE FUNCTION,
DECLARE would become DECLBRE and so on.

Best regards,
--
Daniel Vérité
PostgreSQL-powered mailer: http://www.manitou-mail.org
Twitter: @DanielVerite

On Fri, Sep 11, 2015 at 4:23 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

"seriously flawed" is a bit of a stretch. Most sane developers would not have schema names of one letter.

They usually name a schema something practical, which totally avoids your nit picky exception.

However, if you are that concerned about the "serious flaw", you have the option of using the method

of dumping the schema, editing the dump and reloading. Or, I invite you to use your great skills and

write a better method.

     SELECT replace(qry, source_schema, dest_schema) INTO dest_qry;

Or maybe you can at least mitigate the potential problem a bit by changing this to read:

replace(qry, source_schema || '.', dest_schema || '.') INTO dest_qry; ...

Posting code for public consumption involves accepting constructive criticism and even if the example is contrived I'm doubting the possibility of collision is as close to zero as you think it may be or as close as it could be with a simple re-evaluation of what constraints as imposed on a particular sequence of characters being interpreted as a schema.  You do still end up with a possible false-positive when you have a (column.composite).composite_field expression.

Regular expressions could maybe help here since the leading character is limited too...but less so then the trailing character.

David J.

        Melvin Davidson wrote:

> "seriously flawed" is a bit of a stretch. Most sane developers would not
> have schema names of one letter.
> They usually name a schema something practical, which totally avoids your
> nit picky exception.

That's confusing the example with the problem it shows.

Another example could be:
if the source schema is "public" and the function body contains
   GRANT SELECT on sometable to public;
then this statement would be wrongly altered by replace().

My objection is not about some corner case: it's the general
idea of patching the entire body of a function without a fully-fledged
parser that is dead on arrival.

Best regards,
--
Daniel Vérité
PostgreSQL-powered mailer: http://www.manitou-mail.org
Twitter: @DanielVerite

On 9/12/15 9:38 AM, Daniel Verite wrote:

"seriously flawed" is a bit of a stretch. Most sane developers would not
>have schema names of one letter.
>They usually name a schema something practical, which totally avoids your
>nit picky exception.

That's confusing the example with the problem it shows.

Another example could be:
if the source schema is "public" and the function body contains
    GRANT SELECT on sometable to public;
then this statement would be wrongly altered by replace().

Well, the new version actually fixes that. But you could still trip this up, certainly in the functions. IE:

CREATE FUNCTION ...
  SELECT old.field FROM old.old;

That will end up as

  SELECT new.field FROM new.old

which won't work.

My objection is not about some corner case: it's the general
idea of patching the entire body of a function without a fully-fledged
parser that is dead on arrival.

ISTM that's also the biggest blocker for allowing extensions that refer to other schemas to be relocatable. It would be interesting if we had some way to handle this inside function bodies, perhaps via something equivalent to @extschema@.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com

Jim,

Have you actually tried this, or is it just a theory? AFAIK, the function will work because only the schema name is changed.. So please provide

a full working example of a function that fails and I will attempt a solution.

On Mon, Sep 14, 2015 at 6:36 PM, Jim Nasby <Jim.Nasby@bluetreble.com> wrote:

On 9/12/15 9:38 AM, Daniel Verite wrote:

"seriously flawed" is a bit of a stretch. Most sane developers would not
>have schema names of one letter.
>They usually name a schema something practical, which totally avoids your
>nit picky exception.

That's confusing the example with the problem it shows.

Another example could be:
if the source schema is "public" and the function body contains
    GRANT SELECT on sometable to public;
then this statement would be wrongly altered by replace().

Well, the new version actually fixes that. But you could still trip this up, certainly in the functions. IE:

CREATE FUNCTION ...
  SELECT old.field FROM old.old;

That will end up as

  SELECT new.field FROM new.old

which won't work.

My objection is not about some corner case: it's the general
idea of patching the entire body of a function without a fully-fledged
parser that is dead on arrival.

ISTM that's also the biggest blocker for allowing extensions that refer to other schemas to be relocatable. It would be interesting if we had some way to handle this inside function bodies, perhaps via something equivalent to @extschema@.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

On 9/14/15 8:02 PM, Melvin Davidson wrote:

Actually, on further thought, you example shows that it works correctly
because we do want all references to the old schema to be changed to the
new schema, since all copies of functions will now reside in the new
schema. Otherwise, there is no point of duplicating those functions.

Read my example again:

  SELECT old.field FROM old.old;

That will end up as

  SELECT new.field FROM new.old

Which will give you this error:

ERROR:  missing FROM-clause entry for table "new"
LINE 1: SELECT new.field FROM new.old;

Even if you could fix that, there's yet more problems you'll run into, like if someone has a plpgsql block with the same name as the old schema.

I'm not trying to denigrate the work you and others have put into this script, but everyone should be aware that it's impossible to create a robust solution without a parser. Unfortunately, you could end up with a function that still compiles but does something rather different after the move. That makes the script potentially dangerous (granted, the odds of this are pretty low).

One thing I think would be very interesting is a parser that preserves whitespace and comments. That would allow us to store a parsed version of (at least plpgsql and sql) functions. The same technique would also be handy for views. This would allow a lot (all?) other renames to propagate to functions instead of breaking them (as currently happens).

Another option is supporting some kind of official way to specially designate database objects in any procedure language (ie, the @schema@ syntax that extensions use). That would make it possible to rename properly written functions without adverse side effects.

--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com

I still do not see any problem. The whole purpose of the function is to copy ALL sequences , tables and functions to "new" schema, so new.old WILL exist.

I don't see how you can possibly write a function that references a schema that does not yet exist!

Again, please provide a _working_ example of what you think the problem is.

 

Melvin,

 

This statement:

 

SELECT old.field FROM old.old;

 

selects column “field” from table “old” which is in schema “old”.

 

Your script converts it into:

 

SELECT new.field FROM new.old

 

which will try to select column “field” from table “new” in schema “new”.

The obvious problem is that there is no table “new” in schema “new”, the table will still be called “old”.

 

Jim’s example is very similar to what I provided a few days ago.

 

Regards,

Igor Neyman

 

 

That is correct. But table old will NOT be converted to new because

only the schema name is converted. And table "old" WILL exist because it will also be copied.

I have tested and it works properly.

Please do not provide hypothetical examples. Give me an actual working example that causes the problem.

This statement:

SELECT old.field FROM old.old;

selects column “field” from table “old” which is in schema “old”.

Your script converts it into:

SELECT new.field FROM new.old

which will try to select column “field” from table “old” in schema “new”.

 

Again:

SELECT new.field

means select column “field” from table “new”, which does not exists.

Not sure, what other example you need.

Regards,

Igor Neyman

To make the casual user's life easier, in the face of this reality, it would nice if the routine would generate a reasonably attempted "diff" between the two so that all changes can be reviewed in a structured manner aided by correctly configured tools and advice.

On Tue, Sep 15, 2015 at 12:20 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

Igor,
I understand your point, however, I have spent over a week making a function
that previously did very little do a lot.

Naming a table the same as a schema is a very silly idea.

Unless you care to take the time to provide a full

schema, and function that fails for reasonable , practical design

I will ignore all further comments.

On Tue, Sep 15, 2015 at 9:55 AM, Igor Neyman <ineyman@perceptron.com> wrote:

 

That is correct. But table old will NOT be converted to new because

only the schema name is converted. And table "old" WILL exist because it will also be copied.

I have tested and it works properly.

Please do not provide hypothetical examples. Give me an actual working example that causes the problem.

This statement:

SELECT old.field FROM old.old;

selects column “field” from table “old” which is in schema “old”.

Your script converts it into:

SELECT new.field FROM new.old

which will try to select column “field” from table “old” in schema “new”.

 

Again:

SELECT new.field

means select column “field” from table “new”, which does not exists.

Not sure, what other example you need.

Regards,

Igor Neyman

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

David,

Yes, it would be nice, but

1. I am still working also on bringing over the comments for various objects

2. What you request is currently beyond my capability. Not to mention that there already

    are existing tools that do that, albeit they are not free.

On Tue, Sep 15, 2015 at 12:27 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:

To make the casual user's life easier, in the face of this reality, it would nice if the routine would generate a reasonably attempted "diff" between the two so that all changes can be reviewed in a structured manner aided by correctly configured tools and advice.

On Tue, Sep 15, 2015 at 12:20 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

Igor,
I understand your point, however, I have spent over a week making a function
that previously did very little do a lot.

Naming a table the same as a schema is a very silly idea.

Unless you care to take the time to provide a full

schema, and function that fails for reasonable , practical design

I will ignore all further comments.

On Tue, Sep 15, 2015 at 9:55 AM, Igor Neyman <ineyman@perceptron.com> wrote:

 

That is correct. But table old will NOT be converted to new because

only the schema name is converted. And table "old" WILL exist because it will also be copied.

I have tested and it works properly.

Please do not provide hypothetical examples. Give me an actual working example that causes the problem.

This statement:

SELECT old.field FROM old.old;

selects column “field” from table “old” which is in schema “old”.

Your script converts it into:

SELECT new.field FROM new.old

which will try to select column “field” from table “old” in schema “new”.

 

Again:

SELECT new.field

means select column “field” from table “new”, which does not exists.

Not sure, what other example you need.

Regards,

Igor Neyman

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

Hello,

I had to make 2 changes to get it running:

 

line 193:

-  REPLACE(column_default::text, quote_ident(source_schema) || '.', quote_ident(dest_schema || '.') )

+ REPLACE(column_default::text, quote_ident(source_schema) || '.', quote_ident(dest_schema) || '.' )

 

line 319

-  SELECT replace(v_def, ' ON ', ' ON ' || quote_ident(dest_schema) || '.') INTO dest_qry;

+ SELECT replace(v_def, ' ON ' || quote_ident(source_schema), ' ON ' || quote_ident(dest_schema) ) INTO dest_qry;

 

 

moreover, you don't take care of the column statistic targets

(i.e. ALTER TABLE t ALTER COLUMN c SET STATISTICS n;)

 

 

regards,

 

Marc Mamin

 

 

From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Melvin Davidson
Sent: Donnerstag, 17. September 2015 15:48
To: David G. Johnston
Cc: Igor Neyman; Jim Nasby; Daniel Verite; pgsql-general@postgresql.org
Subject: Re: [GENERAL] clone_schema function

 

Attached is hopefully the final version of

 FUNCTION clone_schema(text, text, boolean)
 
 This function now does the following:
 1. Checks that the source schema exists and the destination does not.
 2. Creates the destination schema
 3. Copies all sequences, tables, indexes, rules, triggers, data(optional),
     views & functions from the source schema to the destination schema
 4. Optionally copies records from source schema tables to destination tabled. (boolean)
 5. Copies comments for source schema and all sequences, tables, functions, rules   and triggers;
 
 If you discover a problem with this function, then kindly advise me what it is
 and attach a script (SQL dump) to duplicate it. If you also have a fix, that is
 even better.
 
 However, if you "think" there is a problem that occurs when
 A. The moon is full
 B. You have blood type A/B negative
 C. You have a table the same name as your database and schema
 D. All you tables have column "id" in them
 E. You've had 16 beers and 4 oxycodones
 F. Your meth supplier raised the price
 
 then do not contact me. Instead, run, do not walk,  immediately to your
 psychologist, as you have serious issues in addition to database design problems
 and you should not use this function under any circumstance.
 
 CAVEAT EMPTOR!
 The only known problem with this script is if functions in the source schema
 have a SELECT using the form of tablename.columm, and tablename is the same
 as  source schema, then tablename will be changed to destination schema name.
 However, since good developers and DBA's use the form of alias.column, this
 should rarely be a problem.

 

On Tue, Sep 15, 2015 at 12:37 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

David,

Yes, it would be nice, but

1. I am still working also on bringing over the comments for various objects

2. What you request is currently beyond my capability. Not to mention that there already

    are existing tools that do that, albeit they are not free.

 

On Tue, Sep 15, 2015 at 12:27 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:

To make the casual user's life easier, in the face of this reality, it would nice if the routine would generate a reasonably attempted "diff" between the two so that all changes can be reviewed in a structured manner aided by correctly configured tools and advice.

 

On Tue, Sep 15, 2015 at 12:20 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

Igor,
I understand your point, however, I have spent over a week making a function
that previously did very little do a lot.

Naming a table the same as a schema is a very silly idea.

Unless you care to take the time to provide a full

schema, and function that fails for reasonable , practical design

I will ignore all further comments.

 

On Tue, Sep 15, 2015 at 9:55 AM, Igor Neyman <ineyman@perceptron.com> wrote:

 

That is correct. But table old will NOT be converted to new because

only the schema name is converted. And table "old" WILL exist because it will also be copied.

I have tested and it works properly.

Please do not provide hypothetical examples. Give me an actual working example that causes the problem.

This statement:

SELECT old.field FROM old.old;

selects column “field” from table “old” which is in schema “old”.

Your script converts it into:

SELECT new.field FROM new.old

which will try to select column “field” from table “old” in schema “new”.

 

Again:

SELECT new.field

means select column “field” from table “new”, which does not exists.

Not sure, what other example you need.

Regards,

Igor Neyman

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

 

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

---

Von: Melvin Davidson [melvin6925@gmail.com]
Gesendet: Donnerstag, 17. September 2015 17:11
An: Marc Mamin
Cc: pgsql-general@postgresql.org
Betreff: Re: [GENERAL] clone_schema function

Thanks,

>I'm not sure why you had trouble with the REPLACE(), as I did extensive testing and it was working as coded.

might be that my modification is required when ( and only when ?) the source_schema is not part of the current search_path.
This is just a guess, I only gave your code a quick try ...

>As for SET STATISTICS, I'm guessing that is a glitch in the CREATE TABLE .... LIKE option.
Yes, we can see it as an incomplete feature.

regards,

Marc Mamin

On Thu, Sep 17, 2015 at 11:05 AM, Marc Mamin <M.Mamin@intershop.de> wrote:

Hello,

I had to make 2 changes to get it running:

 

line 193:

-  REPLACE(column_default::text, quote_ident(source_schema) || '.', quote_ident(dest_schema || '.') )

+ REPLACE(column_default::text, quote_ident(source_schema) || '.', quote_ident(dest_schema) || '.' )

 

line 319

-  SELECT replace(v_def, ' ON ', ' ON ' || quote_ident(dest_schema) || '.') INTO dest_qry;

+ SELECT replace(v_def, ' ON ' || quote_ident(source_schema), ' ON ' || quote_ident(dest_schema) ) INTO dest_qry;

 

 

moreover, you don't take care of the column statistic targets

(i.e. ALTER TABLE t ALTER COLUMN c SET STATISTICS n;)

 

 

regards,

 

Marc Mamin

 

 

From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Melvin Davidson
Sent: Donnerstag, 17. September 2015 15:48
To: David G. Johnston
Cc: Igor Neyman; Jim Nasby; Daniel Verite; pgsql-general@postgresql.org
Subject: Re: [GENERAL] clone_schema function

 

Attached is hopefully the final version of

 FUNCTION clone_schema(text, text, boolean)
 
 This function now does the following:
 1. Checks that the source schema exists and the destination does not.
 2. Creates the destination schema
 3. Copies all sequences, tables, indexes, rules, triggers, data(optional),
     views & functions from the source schema to the destination schema
 4. Optionally copies records from source schema tables to destination tabled. (boolean)
 5. Copies comments for source schema and all sequences, tables, functions, rules   and triggers;
 
 If you discover a problem with this function, then kindly advise me what it is
 and attach a script (SQL dump) to duplicate it. If you also have a fix, that is
 even better.
 
 However, if you "think" there is a problem that occurs when
 A. The moon is full
 B. You have blood type A/B negative
 C. You have a table the same name as your database and schema
 D. All you tables have column "id" in them
 E. You've had 16 beers and 4 oxycodones
 F. Your meth supplier raised the price
 
 then do not contact me. Instead, run, do not walk,  immediately to your
 psychologist, as you have serious issues in addition to database design problems
 and you should not use this function under any circumstance.
 
 CAVEAT EMPTOR!
 The only known problem with this script is if functions in the source schema
 have a SELECT using the form of tablename.columm, and tablename is the same
 as  source schema, then tablename will be changed to destination schema name.
 However, since good developers and DBA's use the form of alias.column, this
 should rarely be a problem.

 

On Tue, Sep 15, 2015 at 12:37 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

David,

Yes, it would be nice, but

1. I am still working also on bringing over the comments for various objects

2. What you request is currently beyond my capability. Not to mention that there already

    are existing tools that do that, albeit they are not free.

 

On Tue, Sep 15, 2015 at 12:27 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:

To make the casual user's life easier, in the face of this reality, it would nice if the routine would generate a reasonably attempted "diff" between the two so that all changes can be reviewed in a structured manner aided by correctly configured tools and advice.

 

On Tue, Sep 15, 2015 at 12:20 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

Igor,
I understand your point, however, I have spent over a week making a function
that previously did very little do a lot.

Naming a table the same as a schema is a very silly idea.

Unless you care to take the time to provide a full

schema, and function that fails for reasonable , practical design

I will ignore all further comments.

 

On Tue, Sep 15, 2015 at 9:55 AM, Igor Neyman <ineyman@perceptron.com> wrote:

 

That is correct. But table old will NOT be converted to new because

only the schema name is converted. And table "old" WILL exist because it will also be copied.

I have tested and it works properly.

Please do not provide hypothetical examples. Give me an actual working example that causes the problem.

This statement:

SELECT old.field FROM old.old;

selects column “field” from table “old” which is in schema “old”.

Your script converts it into:

SELECT new.field FROM new.old

which will try to select column “field” from table “old” in schema “new”.

 

Again:

SELECT new.field

means select column “field” from table “new”, which does not exists.

Not sure, what other example you need.

Regards,

Igor Neyman

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

 

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

Revised to add rules after all tables are create to avoid error where table referenced in rule was not created yet.

Added copying of column statistics with thanks to Marc Mamin  for pointing that out.

On Thu, Sep 17, 2015 at 12:06 PM, Marc Mamin <M.Mamin@intershop.de> wrote:

---

Von: Melvin Davidson [melvin6925@gmail.com]
Gesendet: Donnerstag, 17. September 2015 17:11
An: Marc Mamin
Cc: pgsql-general@postgresql.org
Betreff: Re: [GENERAL] clone_schema function

Thanks,

>I'm not sure why you had trouble with the REPLACE(), as I did extensive testing and it was working as coded.

might be that my modification is required when ( and only when ?) the source_schema is not part of the current search_path.
This is just a guess, I only gave your code a quick try ...

>As for SET STATISTICS, I'm guessing that is a glitch in the CREATE TABLE .... LIKE option.
Yes, we can see it as an incomplete feature.

regards,

Marc Mamin

On Thu, Sep 17, 2015 at 11:05 AM, Marc Mamin <M.Mamin@intershop.de> wrote:

Hello,

I had to make 2 changes to get it running:

 

line 193:

-  REPLACE(column_default::text, quote_ident(source_schema) || '.', quote_ident(dest_schema || '.') )

+ REPLACE(column_default::text, quote_ident(source_schema) || '.', quote_ident(dest_schema) || '.' )

 

line 319

-  SELECT replace(v_def, ' ON ', ' ON ' || quote_ident(dest_schema) || '.') INTO dest_qry;

+ SELECT replace(v_def, ' ON ' || quote_ident(source_schema), ' ON ' || quote_ident(dest_schema) ) INTO dest_qry;

 

 

moreover, you don't take care of the column statistic targets

(i.e. ALTER TABLE t ALTER COLUMN c SET STATISTICS n;)

 

 

regards,

 

Marc Mamin

 

 

From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Melvin Davidson
Sent: Donnerstag, 17. September 2015 15:48
To: David G. Johnston
Cc: Igor Neyman; Jim Nasby; Daniel Verite; pgsql-general@postgresql.org
Subject: Re: [GENERAL] clone_schema function

 

Attached is hopefully the final version of

 FUNCTION clone_schema(text, text, boolean)
 
 This function now does the following:
 1. Checks that the source schema exists and the destination does not.
 2. Creates the destination schema
 3. Copies all sequences, tables, indexes, rules, triggers, data(optional),
     views & functions from the source schema to the destination schema
 4. Optionally copies records from source schema tables to destination tabled. (boolean)
 5. Copies comments for source schema and all sequences, tables, functions, rules   and triggers;
 
 If you discover a problem with this function, then kindly advise me what it is
 and attach a script (SQL dump) to duplicate it. If you also have a fix, that is
 even better.
 
 However, if you "think" there is a problem that occurs when
 A. The moon is full
 B. You have blood type A/B negative
 C. You have a table the same name as your database and schema
 D. All you tables have column "id" in them
 E. You've had 16 beers and 4 oxycodones
 F. Your meth supplier raised the price
 
 then do not contact me. Instead, run, do not walk,  immediately to your
 psychologist, as you have serious issues in addition to database design problems
 and you should not use this function under any circumstance.
 
 CAVEAT EMPTOR!
 The only known problem with this script is if functions in the source schema
 have a SELECT using the form of tablename.columm, and tablename is the same
 as  source schema, then tablename will be changed to destination schema name.
 However, since good developers and DBA's use the form of alias.column, this
 should rarely be a problem.

 

On Tue, Sep 15, 2015 at 12:37 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

David,

Yes, it would be nice, but

1. I am still working also on bringing over the comments for various objects

2. What you request is currently beyond my capability. Not to mention that there already

    are existing tools that do that, albeit they are not free.

 

On Tue, Sep 15, 2015 at 12:27 PM, David G. Johnston <david.g.johnston@gmail.com> wrote:

To make the casual user's life easier, in the face of this reality, it would nice if the routine would generate a reasonably attempted "diff" between the two so that all changes can be reviewed in a structured manner aided by correctly configured tools and advice.

 

On Tue, Sep 15, 2015 at 12:20 PM, Melvin Davidson <melvin6925@gmail.com> wrote:

Igor,
I understand your point, however, I have spent over a week making a function
that previously did very little do a lot.

Naming a table the same as a schema is a very silly idea.

Unless you care to take the time to provide a full

schema, and function that fails for reasonable , practical design

I will ignore all further comments.

 

On Tue, Sep 15, 2015 at 9:55 AM, Igor Neyman <ineyman@perceptron.com> wrote:

 

That is correct. But table old will NOT be converted to new because

only the schema name is converted. And table "old" WILL exist because it will also be copied.

I have tested and it works properly.

Please do not provide hypothetical examples. Give me an actual working example that causes the problem.

This statement:

SELECT old.field FROM old.old;

selects column “field” from table “old” which is in schema “old”.

Your script converts it into:

SELECT new.field FROM new.old

which will try to select column “field” from table “old” in schema “new”.

 

Again:

SELECT new.field

means select column “field” from table “new”, which does not exists.

Not sure, what other example you need.

Regards,

Igor Neyman

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

 

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

The script is generating foreign keys which reference tables in the source schema.

I had to change 

219    SELECT 'ALTER TABLE ' || quote_ident(dest_schema) || '.' || quote_ident(rn.relname) 

220                          || ' ADD CONSTRAINT ' || quote_ident(ct.conname) || ' ' || pg_get_constraintdef(ct.oid) || ';'

to 

219    SELECT 'ALTER TABLE ' || quote_ident(dest_schema) || '.' || quote_ident(rn.relname) 

220                         || ' ADD CONSTRAINT ' || quote_ident(ct.conname) || ' ' || replace(pg_get_constraintdef(ct.oid), quote_ident(source_schema) || '.', quote_ident(dest_schema) || '.') || ';'

I'm attaching the updated script.