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https://issues.apache.org/jira/browse/PHOENIX-10?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13892422#comment-13892422
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James Taylor edited comment on PHOENIX-10 at 2/5/14 7:54 PM:
-------------------------------------------------------------
bq. Which mirror? Sorry not aware of it.
Are you aware of our website?
http://phoenix.incubator.apache.org/source.html
Here's an approach to the client-side of detecting array element references. We
only care about them in the select expressions list (i.e.
RowProjector->ColumnProjector->Expression). We'd want to push any
ArrayIndexFunction expressions, through the Scan coprocessor for server-side
evaluation. On the client-side, we'd wrap occurrences of ArrayIndexFunction in
a new expression (similar to ProjectedColumnExpression as described above)
while we're building the RowProjector. We can bundle this logic inside of the
ProjectionCompiler:
- Add a List<KeyValueExpression> arrayKeyValueRefs member variable that'll
collect the array KV references
- Add a List<Expression> arrayIndexFuncRefs member variable that'll collect the
ArrayIndexFunction references
- Add an override for the following method:
public Expression visitLeave(FunctionParseNode node, List<Expression>
children) throws SQLException
- In this method:
{code}
Expression func = super.visitLeave(node,children);
if ArrayIndexFunction.NAME.equals(node.getName()) {
final List<KeyValueExpression> indexKVs = Lists.newArrayList();
// Create anon visitor to find reference to array in a generic way
children.get(0).accept(new KeyValueExpressionVisitor() {
@Override
public Void visit(KeyValueColumnExpression expression) {
if (expression.getDataType().isArray()) {
indexKVs.add(expression);
}
return null;
}
});
if (!indexKVs.isEmpty()) {
// We could try to detect the same ArrayIndexFunction with
the same index
// and then consolidate them, but it's not really worth it.
arrayKeyValueRefs.addAll(indexKVs);
// Add original func to list that'll get passed to server
arrayIndexFuncRefs.add(func);
// Wrap the client-side func that'll lookup by index the
server-side evaluated value
func = wrapFuncInArrayElemRefExpression(func,
arrayIndexFuncRefs.size()-1);
}
}
{code}
- Then you just pass through both arrayIndexFuncRefs and arrayKeyValueRefs in
Scan attributes to the Scan coprocessor
was (Author: jamestaylor):
bq. Which mirror? Sorry not aware of it.
Are you aware of our website?
http://phoenix.incubator.apache.org/source.html
Here's an approach to the client-side of detecting array element references. We
only care about them in the select expressions list (i.e.
RowProjector->ColumnProjector->Expression). We'd want to push any
ArrayIndexFunction expressions, through the Scan coprocessor for server-side
evaluation. On the client-side, we'd wrap occurrences of ArrayIndexFunction in
a new expression (similar to ProjectedColumnExpression as described above)
while we're building the RowProjector. We can bundle this logic inside of the
ProjectionCompiler:
- Add a List<KeyValueExpression> arrayKeyValueRefs member variable that'll
collect the array KV references
- Add a List<Expression> arrayIndexFuncRefs member variable that'll collect the
ArrayIndexFunction references
- Add an override for the following method:
public Expression visitLeave(FunctionParseNode node, List<Expression>
children) throws SQLException
- In this method:
{code}
Expression func = super.visitLeave(node,children);
if ArrayIndexFunction.NAME.equals(node.getName()) {
final List<KeyValueExpression> indexKVs = Lists.newArrayList();
// Create anon visitor to find reference to array in a generic way
children.get(0).accept(new KeyValueExpressionVisitor() {
@Override
public Void visit(KeyValueColumnExpression expression) {
indexKVs.add(expression);
return null;
}
});
if (!indexKVs.isEmpty()) {
// We could try to detect the same ArrayIndexFunction with
the same index
// and then consolidate them, but it's not really worth it.
arrayKeyValueRefs.addAll(indexKVs);
// Add original func to list that'll get passed to server
arrayIndexFuncRefs.add(func);
// Wrap the client-side func that'll lookup by index the
server-side evaluated value
func = wrapFuncInArrayElemRefExpression(func,
arrayIndexFuncRefs.size()-1);
}
}
{code}
- Then you just pass through both arrayIndexFuncRefs and arrayKeyValueRefs in
Scan attributes to the Scan coprocessor
> Push projection of a single ARRAY element to the server
> -------------------------------------------------------
>
> Key: PHOENIX-10
> URL: https://issues.apache.org/jira/browse/PHOENIX-10
> Project: Phoenix
> Issue Type: Improvement
> Reporter: James Taylor
> Assignee: ramkrishna.s.vasudevan
> Attachments: Phoenix-10_1.patch
>
>
> If only a single array element is selected, we'll still return the entire
> array back to the client. Instead, we should push this to the server and only
> return the single array element. The same goes for the reference to an ARRAY
> in the WHERE clause. There's a general HBase fix for this (i.e. the ability
> to define a separate set of key values that will be returned versus key
> values available to filters) that has a patch here, but is deemed not
> possible to pull into the 0.94 branch by @lhofhansl.
> My thought is that we can add a Filter at the end our our filter chain that
> filters out any KeyValues that aren't in the SELECT expressions (i.e. filter
> out if a column is referenced in the WHERE clause, but not in the SELECT
> expressions). This same Filter could handle returning only the elements of
> the array that are referenced in the SELECT expression rather than the entire
> array.
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