rq_head

A piped query generator based on Edgar F. Codd's relational
algebra, and on production experience using 'SQL' and 'dplyr' at big data
scale.  The design represents an attempt to make 'SQL' more teachable by
denoting composition by a sequential pipeline notation instead of nested
queries or functions.   The implementation delivers reliable high
performance data processing on large data systems such as 'Spark',
databases, and 'data.table'. Package features include: data processing trees
or pipelines as observable objects (able to report both columns
produced and columns used), optimized 'SQL' generation as an explicit
user visible table modeling step, plus explicit query reasoning and checking.

John Mount

rquery

Relational Query Generator for Data Manipulation at Scale

 Win-Vector LLC

rq_head function

<dl><dt>db</dt>
<dd>Connection handle</dd>
<dt>table_name</dt>
<dd>character table name</dd>
<dt>...</dt>
<dd>not used, force later argument to bind by name</dd>
<dt>qualifiers</dt>
<dd>optional named ordered vector of strings carrying additional db hierarchy terms, such as schema.</dd>
<dt>limit</dt>
<dd>integer, how many rows to take</dd></dl>

Arguments

Get head of db table — rq_head

<dl>

<dt>db</dt>
<dd>Connection handle</dd>


<dt>table_name</dt>
<dd>character table name</dd>


<dt>...</dt>
<dd>not used, force later argument to bind by name</dd>


<dt>qualifiers</dt>
<dd>optional named ordered vector of strings carrying additional db hierarchy terms, such as schema.</dd>


<dt>limit</dt>
<dd>integer, how many rows to take</dd>

</dl>

rq_head: Get head of db table

Description

Usage

Value

Arguments