// NewRowContainer allocates a new row container.
//
// The acc argument indicates where to register memory allocations by
// this row container. Should probably be created by
// Session.makeSessionBoundAccount() or Session.makeTxnBoundAccount().
//
// The rowCapacity argument indicates how many rows are to be
// expected; it is used to pre-allocate the outer array of row
// references, in the fashion of Go's capacity argument to the make()
// function.
//
// Note that we could, but do not (yet), report the size of the row
// container itself to the monitor in this constructor. This is
// because the various planNodes are not (yet) equipped to call
// Close() upon encountering errors in their constructor (all nodes
// initializing a RowContainer there) and SetLimitHint() (for sortNode
// which initializes a RowContainer there). This would be rather
// error-prone to implement consistently and hellishly difficult to
// test properly. The trade-off is that very large table schemas or
// column selections could cause unchecked and potentially dangerous
// memory growth.
func (p *planner) NewRowContainer(
acc mon.BoundAccount, h ResultColumns, rowCapacity int,
) *RowContainer {
nCols := len(h)
res := &RowContainer{
rows: make([]parser.DTuple, 0, rowCapacity),
numCols: nCols,
varSizedColumns: make([]int, 0, nCols),
memAcc: acc,
}
for i := 0; i < nCols; i++ {
sz, variable := h[i].Typ.Size()
if variable {
res.varSizedColumns = append(res.varSizedColumns, i)
} else {
res.fixedColsSize += int64(sz)
}
}
res.fixedColsSize += int64(unsafe.Sizeof(parser.Datum(nil)) * uintptr(nCols))
return res
}
// NewRowContainer allocates a new row container.
//
// The acc argument indicates where to register memory allocations by
// this row container. Should probably be created by
// Session.makeBoundAccount() or Session.TxnState.makeBoundAccount().
//
// The rowCapacity argument indicates how many rows are to be
// expected; it is used to pre-allocate the outer array of row
// references, in the fashion of Go's capacity argument to the make()
// function.
//
// Note that we could, but do not (yet), report the size of the row
// container itself to the monitor in this constructor. This is
// because the various planNodes are not (yet) equipped to call
// Close() upon encountering errors in their constructor (all nodes
// initializing a RowContainer there) and SetLimitHint() (for sortNode
// which initializes a RowContainer there). This would be rather
// error-prone to implement consistently and hellishly difficult to
// test properly. The trade-off is that very large table schemas or
// column selections could cause unchecked and potentially dangerous
// memory growth.
func NewRowContainer(acc mon.BoundAccount, h ResultColumns, rowCapacity int) *RowContainer {
nCols := len(h)
c := &RowContainer{
numCols: nCols,
memAcc: acc,
preallocChunks: 1,
}
if nCols != 0 {
c.rowsPerChunk = (targetChunkSize + nCols - 1) / nCols
if rowCapacity > 0 {
c.preallocChunks = (rowCapacity + c.rowsPerChunk - 1) / c.rowsPerChunk
}
}
for i := 0; i < nCols; i++ {
sz, variable := h[i].Typ.Size()
if variable {
if c.varSizedColumns == nil {
// Only allocate varSizedColumns if necessary.
c.varSizedColumns = make([]int, 0, nCols)
}
c.varSizedColumns = append(c.varSizedColumns, i)
} else {
c.fixedColsSize += int64(sz)
}
}
// Precalculate the memory used for a chunk, specifically by the Datums in the
// chunk and the slice pointing at the chunk.
c.chunkMemSize = int64(unsafe.Sizeof(parser.Datum(nil))) * int64(c.rowsPerChunk*c.numCols)
c.chunkMemSize += int64(unsafe.Sizeof([]parser.Datum(nil)))
return c
}
// Author: Irfan Sharif ([email protected]) package sql import ( "fmt" "unsafe" "github.com/cockroachdb/cockroach/pkg/sql/mon" "github.com/cockroachdb/cockroach/pkg/sql/parser" ) const ( // targetChunkSize is the target number of Datums in a RowContainer chunk. targetChunkSize = 64 sizeOfDatum = int64(unsafe.Sizeof(parser.Datum(nil))) sizeOfDTuple = int64(unsafe.Sizeof(parser.DTuple(nil))) ) // RowContainer is a container for rows of DTuples which tracks the // approximate amount of memory allocated for row data. // Rows must be added using AddRow(); once the work is done // the Close() method must be called to release the allocated memory. // // TODO(knz): this does not currently track the amount of memory used // for the outer array of DTuple references. type RowContainer struct { numCols int // rowsPerChunk is the number of rows in a chunk; we pack multiple rows in a // single []Datum to reduce the overhead of the slice if we have few columns.
