sql: unreserve MINVALUE and MAXVALUE #31730
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… table names CockroachDB introduced non-standard extensions to its SQL dialect very early in its history, before concerns of compatibility with existing PostgreSQL clients became a priority. When these features were added, new keywords were liberally marked as "reserved", so as to "make the grammar work", and without noticing / care for the fact that this change would make existing valid SQL queries/clients encounter new errors. An example of this: 1. let's make "column families" a thing 2. the syntax `create table(..., constraint xxx family(a,b,c))` is not good enough (although this would not require reserved keywords), we really want also `create table (..., family (a,b,c))` to be possible. 3. oh, the grammar won't let us because "family" is a possible column name? No matter! let's mark "FAMILY" as a reserved name for column/function names. - No concern for the fact that "family" is a perfectly valid English name for things that people want to make an attribute of in inventory / classification tables. - No concern for the fact that reserved column/function names are also reserved for table names. 4. (much later) Clients complaining about the fact they can't call their columns or tables `family` without quoting. Ditto "INDEX", "MINVALUE", "MAXVALUE", and perhaps others. Moral of the story: DO NOT MAKE NEW RESERVED KEYWORDS UNLESS YOU'RE VERY VERY VERY SURE THAT THERE IS NO LEGITIMATE USE FOR THEM IN CLIENT APPS EVER. (An example perhaps: the word "NOTHING" was also marked as reserved, but it's much more unlikely this word will ever be used for something useful.) This patch restores the use of FAMILY, INDEX, NOTHING, MINVALUE and MAXVALUE in table and function names, by introducing an awkward dance in the grammar of keyword non-terminals and database object names. They remain reserved as colum names because of the non-standard CockroachDB extensions. Release note (sql change): It is now again possible to use the keywords FAMILY, MINVALUE, MAXVALUE, INDEX or NOTHING as table names, for compatibility with PostgreSQL.
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The SET statement in the pg dialect is special because it auto-converts identifiers on its RHS to symbolic values or strings. In particular it is meant to support a diversity of special keywords as pseudo-values. This patch ensures that INDEX and NOTHING are accepted on the RHS. Release note (sql change): the names "index" and "nothing" are again accepted in the right-hand-side of the assignment in SET statements, for compatibility with PostgreSQL.
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The keywords MINVALUE and MAXVALUE had been marked as reserved away from being a valid column name to accommodate the CockroachDB-specific "PARTITIONING" syntax. This is unfortunate because these two words are perfectly fine English names for things people may want to have as attributes in their relations. This patch removes the limitation by unreserving the two keywords and handling the special words in the planning code for the partitioning feature. In every other context the two words are not treated specially and handled like any possible column name / identifier. Release note (sql change): It is now again possible to use the keywords MINVALUE and MAXVALUE as column names, for compatibility with PostgreSQL.
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bobvawter
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Oct 23, 2018
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will want also a green light by Nikhil or Dan before merging this one. |
benesch
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Oct 23, 2018
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cool thanks bors r+ |
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Oct 23, 2018
31730: sql: unreserve MINVALUE and MAXVALUE r=knz a=knz First two commits from #31725 and #31731. The keywords MINVALUE and MAXVALUE had been marked as reserved away from being a valid column name to accommodate the CockroachDB-specific "PARTITIONING" syntax. This is unfortunate because these two words are perfectly fine English names for things people may want to have as attributes in their relations. This patch removes the limitation by unreserving the two keywords and handling the special words in the planning code for the partitioning feature. In every other context the two words are not treated specially and handled like any possible column name / identifier. Release note (sql change): It is now again possible to use the keywords MINVALUE and MAXVALUE as column names, for compatibility with PostgreSQL. Co-authored-by: Raphael 'kena' Poss <[email protected]>
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First two commits from #31725 and #31731.
The keywords MINVALUE and MAXVALUE had been marked as reserved away
from being a valid column name to accommodate the CockroachDB-specific
"PARTITIONING" syntax.
This is unfortunate because these two words are perfectly fine English
names for things people may want to have as attributes in their
relations.
This patch removes the limitation by unreserving the two keywords and
handling the special words in the planning code for the partitioning
feature. In every other context the two words are not treated
specially and handled like any possible column name / identifier.
Release note (sql change): It is now again possible to use the
keywords MINVALUE and MAXVALUE as column names, for compatibility with
PostgreSQL.