protected SelectStatement buildAggCommand(SelectStatement in) {
SelectStatement out = CopyVisitor.copy(in);
// we're going to build
// select Name, max(Engine), max(Version), max(Row_format),
// sum(Rows), avg(Avg_row_length), sum(Data_length),
// max(Max_data_length), sum(Index_length),
// sum(Data_free), max(Auto_increment), min(Create_time),
// max(Update_time), max(Check_time),
// max(Collation), null /*Checksum*/, max(Create_options), max(Comment) from temp1 group by Name
// eventually we will build another temp table of rewrite info (visible name, auto_inc values)
// and join
// but for now this is good enough
List<ExpressionNode> proj = new ArrayList<ExpressionNode>();
ExpressionAlias nameColumn = null;
for (ExpressionNode en : out.getProjection()) {
ExpressionAlias ea = (ExpressionAlias) en;
ColumnInstance ci = (ColumnInstance) ea.getTarget();
String cn = ci.getColumn().getName().getUnquotedName().get();
FunctionCall fc = null;
if (maxedColumns.contains(cn)) {
fc = new FunctionCall(FunctionName.makeMax(), ci);
} else if (summedColumns.contains(cn)) {
fc = new FunctionCall(FunctionName.makeSum(), ci);
} else if ("Name".equals(cn)) {
fc = null;
nameColumn = ea;
} else if ("Avg_row_length".equals(cn)) {
fc =
new FunctionCall(
FunctionName.makeRound(), new FunctionCall(FunctionName.makeAvg(), ci));
} else if ("Create_time".equals(cn)) {
fc = new FunctionCall(FunctionName.makeMin(), ci);
} else if ("Checksum".equals(cn)) {
fc = null;
ea =
new ExpressionAlias(
LiteralExpression.makeNullLiteral(),
new NameAlias(ci.getColumn().getName().getUnqualified()),
false);
} else {
throw new SchemaException(Pass.PLANNER, "Unknown show status column: " + cn);
}
if (fc != null) {
ea =
new ExpressionAlias(
fc, new NameAlias(ci.getColumn().getName().getUnqualified()), false);
}
proj.add(ea);
}
out.setProjection(proj);
SortingSpecification ngb = new SortingSpecification(nameColumn.buildAliasInstance(), true);
ngb.setOrdering(Boolean.FALSE);
out.getGroupBysEdge().add(ngb);
return out;
}
