Keywords are words that have a specific meaning in the SQL language. Every SQL statement contains one or more keywords. Although SQL is not case-sensitive with respect to keywords, they are generally shown in uppercase letters throughout this documentation for readability purposes.
If you use a keyword as the name of an identifier or an alias in your SQL statements, you may have to qualify the keyword with
AS or double-quotes. Vertica requires
AS or double-quotes for certain reserved and non-reserved words to prevent confusion with expression syntax, or where the use of a word would be ambiguous.
Reserved Words and Keywords
Many keywords are also reserved words.
Vertica recommends that you not use reserved words as names for objects, or as identifiers. Including reserved words can make your SQL statements confusing. Reserved words that are used as names for objects or identifiers must be enclosed in double-quotes.
All reserved words are also keywords, but Vertica can add reserved words that are not keywords. A reserved word can simply be a word that is reserved for future use.
Non-reserved keywords have a special meaning in some contexts, but can be used as identifiers in others. You can use non-reserved keywords as aliases—for example,
=> SELECT my_node AS SOURCE FROM nodes;
Vertica uses several non-reserved keywords in directed queries to specify special join types. You can use these keywords as table aliases only if they are double-quoted; otherwise, double-quotes can be omitted:
Viewing the List of Reserved and Non-reserved Keywords
To view the current list of Vertica reserved and non-reserved words, query system table
KEYWORDS. Vertica lists keywords alphabetically and identifies them as reserved (R) or non-reserved (N).
For example, the following query gets all reserved keywords that begin with B:
=> SELECT * FROM keywords WHERE reserved = 'R' AND keyword ilike 'B%'; keyword | reserved ---------+---------- BETWEEN | R BIGINT | R BINARY | R BIT | R BOOLEAN | R BOTH | R (6 rows)