SpGistInnerTuple
spgFormInnerTuple(SpGistState *state, bool hasPrefix, Datum prefix, int nNodes, IndexTuple *nodes)
{
SpGistInnerTuple tup;
unsigned int size;
int i;
char *ptr;
size = SGITHDRSZ;
if (hasPrefix)
size += getTypeLength(&state->attPrefixType, prefix);
for(i=0; i<nNodes; i++)
size += IndexTupleSize(nodes[i]);
Assert(size < 0xffff);
tup = palloc0(size);
tup->hasPrefix = !!hasPrefix;
tup->nNodes = nNodes;
tup->size = size;
if (tup->hasPrefix)
memcpyDatum(SGITDATAPTR(tup), &state->attPrefixType, prefix);
ptr= (char*)SGITNODEPTR(tup, state);
for(i=0; i<nNodes; i++)
{
IndexTuple node = nodes[i];
memcpy(ptr, node, IndexTupleSize(node));
ptr += IndexTupleSize(node);
}
return tup;
}
/*
* Construct an inner tuple containing the given prefix and node array
*/
SpGistInnerTuple
spgFormInnerTuple(SpGistState *state, bool hasPrefix, Datum prefix,
int nNodes, SpGistNodeTuple *nodes)
{
SpGistInnerTuple tup;
unsigned int size;
unsigned int prefixSize;
int i;
char *ptr;
/* Compute size needed */
if (hasPrefix)
prefixSize = SpGistGetTypeSize(&state->attPrefixType, prefix);
else
prefixSize = 0;
size = SGITHDRSZ + prefixSize;
/* Note: we rely on node tuple sizes to be maxaligned already */
for (i = 0; i < nNodes; i++)
size += IndexTupleSize(nodes[i]);
/*
* Ensure that we can replace the tuple with a dead tuple later. This
* test is unnecessary given current tuple layouts, but let's be safe.
*/
if (size < SGDTSIZE)
size = SGDTSIZE;
/*
* Inner tuple should be small enough to fit on a page
*/
if (size > SPGIST_PAGE_CAPACITY - sizeof(ItemIdData))
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("SP-GiST inner tuple size %lu exceeds maximum %lu",
(unsigned long) size,
(unsigned long) (SPGIST_PAGE_CAPACITY - sizeof(ItemIdData))),
errhint("Values larger than a buffer page cannot be indexed.")));
/*
* Check for overflow of header fields --- probably can't fail if the
* above succeeded, but let's be paranoid
*/
if (size > SGITMAXSIZE ||
prefixSize > SGITMAXPREFIXSIZE ||
nNodes > SGITMAXNNODES)
elog(ERROR, "SPGiST inner tuple header field is too small");
/* OK, form the tuple */
tup = (SpGistInnerTuple) palloc0(size);
tup->nNodes = nNodes;
tup->prefixSize = prefixSize;
tup->size = size;
if (hasPrefix)
memcpyDatum(SGITDATAPTR(tup), &state->attPrefixType, prefix);
ptr = (char *) SGITNODEPTR(tup);
for (i = 0; i < nNodes; i++)
{
SpGistNodeTuple node = nodes[i];
memcpy(ptr, node, IndexTupleSize(node));
ptr += IndexTupleSize(node);
}
return tup;
}
