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## PostgreSQLSupport.R
## $Id$
## This package was developed as a part of Summer of Code program organized by Google.
## Thanks to David A. James & Saikat DebRoy, the authors of RMySQL package.
## Code from RMySQL package was reused with the permission from the authors.
## Also Thanks to my GSoC mentor Dirk Eddelbuettel for helping me in the development.
## create a PostgreSQL database connection manager. By default we allow
## up to "max.con" connections and single fetches of up to "fetch.default.rec"
## records. These settings may be changed by re-loading the driver
## using the "force.reload" = T flag (note that this will close all
## currently open connections).
## Returns an object of class "PostgreSQLManger".
## Note: This class is a singleton.
postgresqlInitDriver <- function(max.con=16, fetch.default.rec = 500, force.reload=FALSE) {
if(fetch.default.rec<=0)
stop("default num of records per fetch must be positive")
config.params <- as.integer(c(max.con, fetch.default.rec))
force <- as.logical(force.reload)
drvId <- .Call(RS_PostgreSQL_init, config.params, force)
new("PostgreSQLDriver", Id = drvId)
}
postgresqlCloseDriver <- function(drv, ...) {
if(!isPostgresqlIdCurrent(drv))
return(TRUE)
drvId <- as(drv, "integer")
.Call(RS_PostgreSQL_closeManager, drvId)
}
## Print out nicely a brief description of the connection Driver
postgresqlDescribeDriver <- function(obj, verbose = FALSE, ...) {
info <- dbGetInfo(obj)
print(obj)
cat(" Driver name: ", info$drvName, "\n")
cat(" Max connections:", info$length, "\n")
cat(" Conn. processed:", info$counter, "\n")
cat(" Default records per fetch:", info$"fetch_default_rec", "\n")
if(verbose){
cat(" DBI API version: ", dbGetDBIVersion(), "\n")
## cat(" PostgreSQL client version: ", info$clientVersion, "\n") Feature absent
}
cat(" Open connections:", info$"num_con", "\n")
if(verbose && !is.null(info$connectionIds)){
for(i in seq_along(info$connectionIds)){
cat(" ", i, " ")
print(info$connectionIds[[i]])
}
}
invisible(NULL)
}
postgresqlDriverInfo <- function(obj, what="", ...) {
if(!isPostgresqlIdCurrent(obj))
stop(paste("expired", class(obj)))
drvId <- as(obj, "integer")
info <- .Call(RS_PostgreSQL_managerInfo, drvId)
## replace drv/connection id w. actual drv/connection objects
conObjs <- vector("list", length = info$"num_con")
ids <- info$connectionIds
for(i in seq_along(ids))
conObjs[[i]] <- new("PostgreSQLConnection", Id = c(drvId, ids[i]))
info$connectionIds <- conObjs
info$managerId <- new("PostgreSQLDriver", Id = drvId)
if(!missing(what))
info[what]
else
info
}
## All NULL values are changed to empty strings ("").
## These are treated as default values.
postgresqlNewConnection <- function(drv, user = "", password = "",
host = "", dbname = "",
port = "", tty = "", options = "", forceISOdate=TRUE) {
if(!isPostgresqlIdCurrent(drv))
stop("expired manager")
if(is.null(user))
user=""
if(is.null(password))
password=""
if(is.null(host))
host=""
if(is.null(dbname))
dbname=""
if(is.null(port))
port=""
if(is.null(tty))
tty=""
if(is.null(options))
options=""
con.params <- as.character(c(user, password, host,
dbname, port,
tty, options))
drvId <- as(drv, "integer")
conId <- .Call(RS_PostgreSQL_newConnection, drvId, con.params)
con <- new("PostgreSQLConnection", Id = conId)
if(forceISOdate){
dbGetQuery(con, "set datestyle to ISO")
}
con
}
postgresqlCloneConnection <- function(con, ...) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
newId <- .Call(RS_PostgreSQL_cloneConnection, conId)
new("PostgreSQLConnection", Id = newId)
}
postgresqlDescribeConnection <- function(obj, verbose = FALSE, ...) {
info <- dbGetInfo(obj)
print(obj)
cat(" User:", info$user, "\n")
cat(" Host:", info$host, "\n")
cat(" Dbname:", info$dbname, "\n")
## cat(" Connection type:", info$conType, "\n") function absent
if(verbose){
cat(" PostgreSQL server version: ", info$serverVersion, "\n")
## cat(" PostgreSQL client version: ",
## dbGetInfo(as(obj, "PostgreSQLDriver"), what="clientVersion")[[1]], "\n") feature absent
cat(" PostgreSQL protocol version: ", info$protocolVersion, "\n")
cat(" PostgreSQL server thread id: ", info$threadId, "\n")
}
if (length(info$rsId)>0) {
for (i in seq_along(info$rsId)) {
cat(" ", i, " ")
print(info$rsId[[i]])
}
} else {
cat(" No resultSet available\n")
}
invisible(NULL)
}
postgresqlCloseConnection <- function(con, ...) {
if(!isPostgresqlIdCurrent(con))
return(TRUE)
rs <- dbListResults(con)
if(length(rs)>0){
if(dbHasCompleted(rs[[1]]))
dbClearResult(rs[[1]])
else
stop("connection has pending rows (close open results set first)")
}
conId <- as(con, "integer")
.Call(RS_PostgreSQL_closeConnection, conId)
}
postgresqlConnectionInfo <- function(obj, what="", ...) {
if(!isPostgresqlIdCurrent(obj))
stop(paste("expired", class(obj), deparse(substitute(obj))))
id <- as(obj, "integer")
info <- .Call(RS_PostgreSQL_connectionInfo, id)
rsId <- vector("list", length = length(info$rsId))
for(i in seq_along(info$rsId))
rsId[[i]] <- new("PostgreSQLResult", Id = c(id, info$rsId[i]))
info$rsId <- rsId
if(!missing(what))
info[what]
else
info
}
## checks for any open resultsets, and closes them if completed.
## the statement is then executed on the connection, and returns
## whether it executed without an error or not.
postgresqlTransactionStatement <- function(con, statement) {
## are there resultSets pending on con?
if(length(dbListResults(con)) > 0){
res <- dbListResults(con)[[1]]
if(!dbHasCompleted(res)){
stop("connection with pending rows, close resultSet before continuing")
}
dbClearResult(res)
}
rc <- try(dbGetQuery(con, statement))
!inherits(rc, ErrorClass)
}
## submits the sql statement to PostgreSQL and creates a
## dbResult object if the SQL operation does not produce
## output, otherwise it produces a resultSet that can
## be used for fetching rows.
postgresqlExecStatement <- function(con, statement, params, ...) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
statement <- as(statement, "character")
if(missing(params)){
rsId <- .Call(RS_PostgreSQL_exec, conId, statement)
}else{
rsId <- .External(RS_PostgreSQL_pqexecparams, conId, statement, as(params, "character"), ...)
}
new("PostgreSQLResult", Id = rsId)
}
postgresqlEscapeStrings <- function(con, preescapedstring) {
conId <- as(con, "integer")
preescapedstring <- as(preescapedstring, "character")
escapedstring <- .Call(RS_PostgreSQL_escape, conId, preescapedstring)
return(escapedstring)
}
postgresqlEscapeBytea <- function(con, raw_data) {
conId <- as(con, "integer")
raw_data <- as(raw_data, "raw")
escapedstring <- .Call(RS_PostgreSQL_escape_bytea, conId, raw_data)
return(escapedstring)
}
postgresqlUnescapeBytea <- function(escapedbytea) {
escapedbytea <- as(escapedbytea, "character")
raw_data <- .Call(RS_PostgreSQL_unescape_bytea, escapedbytea)
return(raw_data)
}
postgresqlpqExec <- function(con, statement) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
statement <- as(statement, "character")
.Call(RS_PostgreSQL_pqexec, conId, statement)
}
postgresqlpqExecParams <- function(con, statement, ...) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
statement <- as(statement, "character")
.External(RS_PostgreSQL_pqexecparams, conId, statement, ...)
}
postgresqlCopyIn <- function(con, filename) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
filename <- as(filename, "character")
.Call(RS_PostgreSQL_CopyIn, conId, filename)
}
postgresqlCopyInDataframe <- function(con, dataframe) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
nrow <- nrow(dataframe)
p <- ncol(dataframe)
.Call(RS_PostgreSQL_CopyInDataframe, conId, dataframe, nrow, p)
}
postgresqlgetResult <- function(con) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
conId <- as(con, "integer")
rsId <- .Call(RS_PostgreSQL_getResult, conId)
new("PostgreSQLResult", Id = rsId)
}
## helper function: it exec's *and* retrieves a statement. It should
## be named somehting else.
postgresqlQuickSQL <- function(con, statement, ...) {
if(!isPostgresqlIdCurrent(con))
stop(paste("expired", class(con)))
rsList <- dbListResults(con)
if (length(rsList)>0){ # clear results
dbClearResult(rsList[[1]])
}
rs <- try(dbSendQuery(con, statement, ...))
if (inherits(rs, ErrorClass)){
warning("Could not create execute: ", statement)
return(NULL)
}
if(dbHasCompleted(rs)){
dbClearResult(rs) ## no records to fetch, we're done
invisible()
return(data.frame()) # data.frame of 0 row 0 columns
}
res <- fetch(rs, n = -1)
if(dbHasCompleted(rs))
dbClearResult(rs)
else
warning("pending rows") # shouldn't occur...
res
}
postgresqlDescribeFields <- function(res, ...) {
flds <- dbGetInfo(res, "fieldDescription")[[1]][[1]]
if(!is.null(flds)){
flds$Sclass <- .Call(RS_DBI_SclassNames, flds$Sclass)
## -------
## This is actually a bug introduced deliberately. In dbGetInfo, it displays the Sclass for Date/Time datatypes in Pg
## as character. But in dbColumnInfo, it displays it as 'POSIXct'. This is because there is no
## datatype corresponding to Date/Time defined in R-defines.h & R-internals.h
for(i in 1:length(flds$type)) {
if(flds$type[[i]] == 1114) {
flds$Sclass[[i]] = "POSIXct";
} else if(flds$type[[i]] == 1082) {
flds$Sclass[[i]] = "Date";
} else if(flds$type[[i]] == 1184) {
flds$Sclass[[i]] = "POSIXct";
}
}
## -------
flds$type <- .Call(RS_PostgreSQL_typeNames, as.integer(flds$type))
## no factors
structure(flds, row.names = paste(seq_along(flds$type)),
class = "data.frame")
}
else data.frame(flds)
}
## (Experimental)
## This function is meant to handle somewhat gracefully(?) large amounts
## of data from the DBMS by bringing into R manageable chunks (about
## batchSize records at a time, but not more than maxBatch); the idea
## is that the data from individual groups can be handled by R, but
## not all the groups at the same time.
##
## dbApply apply functions to groups of rows coming from a remote
## database resultSet upon the following fetching events:
## begin (prior to fetching the first record)
## group.begin (the record just fetched begins a new group)
## new_record (a new record just fetched)
## group.end (the record just fetched ends the current group)
## end (the record just fetched is the very last record)
##
## The "begin", "begin.group", etc., specify R functions to be
## invoked upon the corresponding events. (For compatibility
## with other apply functions the arg FUN is used to specify the
## most common case where we only specify the "group.end" event.)
##
## The following describes the exact order and form of invocation for the
## various callbacks in the underlying C code. All callback function
## (except FUN) are optional.
## begin()
## group.begin(group.name)
## new.record(df.record)
## FUN(df.group, group.name) (aka group.end)
## end()
##
## TODO: (1) add argument output=F/T to suppress the creation of
## an expensive(?) output list.
## (2) allow INDEX to be a list as in tapply()
## (3) should we implement a simplify argument, as in sapply()?
## (4) should report (instead of just warning) when we're forced
## to handle partial groups (groups larger than maxBatch).
## (5) extend to the case where even individual groups are too
## big for R (as in incrementatl quantiles).
## (6) Highly R-dependent, not sure yet how to port it to S-plus.
##
postgresqlDBApply <- function(res, INDEX, FUN = stop("must specify FUN"),
begin = NULL,
group.begin = NULL,
new.record = NULL,
end = NULL,
batchSize = 100, maxBatch = 1e6,
..., simplify = TRUE) {
if(dbHasCompleted(res))
stop("result set has completed")
if(is.character(INDEX)){
flds <- tolower(as.character(dbColumnInfo(res)$name))
INDEX <- match(tolower(INDEX[1]), flds, 0)
}
if(INDEX<1)
stop(paste("INDEX field", INDEX, "not in result set"))
null.or.fun <- function(fun) { # get fun obj, but a NULL is ok
if(is.null(fun))
fun
else
match.fun(fun)
}
begin <- null.or.fun(begin)
group.begin <- null.or.fun(group.begin)
group.end <- null.or.fun(FUN) ## probably this is the most important
end <- null.or.fun(end)
new.record <- null.or.fun(new.record)
rsId <- as(res, "integer")
con <- as(res, "PostgreSQLConnection")
on.exit({
rc <- dbGetException(con)
if(!is.null(rc$errorNum) && rc$errorNum!=0)
cat("dbApply aborted with PostgreSQL error ", rc$errorNum,
" (", rc$errorMsg, ")\n", sep = "")
})
## BEGIN event handler (re-entrant, only prior to reading first row)
if(!is.null(begin) && dbGetRowCount(res)==0)
begin()
rho <- environment()
funs <- list(begin = begin, end = end,
group.begin = group.begin,
group.end = group.end, new.record = new.record)
out <- .Call(RS_PostgreSQL_dbApply,
rs = rsId,
INDEX = as.integer(INDEX-1),
funs, rho, as.integer(batchSize), as.integer(maxBatch))
if(!is.null(end) && dbHasCompleted(res))
end()
out
}
## Fetch at most n records from the opened resultSet (n = -1 means
## all records, n=0 means extract as many as "default_fetch_rec",
## as defined by PostgreSQLDriver (see describe(drv, T)).
## The returned object is a data.frame.
## Note: The method dbHasCompleted() on the resultSet tells you whether
## or not there are pending records to be fetched.
##
## TODO: Make sure we don't exhaust all the memory, or generate
## an object whose size exceeds option("object.size"). Also,
## are we sure we want to return a data.frame?
postgresqlFetch <- function(res, n=0, ...) {
n <- as(n, "integer")
rsId <- as(res, "integer")
rel <- .Call(RS_PostgreSQL_fetch, rsId, nrec = n)
## create running row index as of previous fetch (if any)
cnt <- dbGetRowCount(res)
nrec <- length(rel[[1]])
indx <- seq.int(from = cnt - nrec + 1, length.out = nrec)
attr(rel, "row.names") <- indx
if(usingR())
class(rel) <- "data.frame"
else
oldClass(rel) <- "data.frame"
drop_infinity <- function(x){ if(is.na(x)) NA else if(x == 'infinity' || x == '-infinity'){warning(x, ": infinity in date data detected") ; NA} else x}
flds <- dbGetInfo(res)$fieldDescription[[1]]$type
if(length(rel[,1])>0){
for(i in 1:length(flds)) {
if(flds[[i]] == 1114) { ## 1114 corresponds to Timestamp without TZ (mapped to POSIXct class)
rel[,i] <- sapply(rel[,i], drop_infinity)
rel[,i] <- as.POSIXct(rel[,i])
} else if(flds[[i]] == 1082) { ## 1082 corresponds to Date (mapped to Date class)
rel[,i] <- sapply(rel[,i], drop_infinity)
rel[,i] <- as.Date(rel[,i])
} else if(flds[[i]] == 1184) { ## 1184 corresponds to Timestamp with TimeZone
rel[,i] <- sapply(rel[,i], drop_infinity)
rel[,i] <- as.POSIXct(sub('([+-]..)$', '\\100', sub(':(..)$','\\1' ,rel[,i])), format="%Y-%m-%d %H:%M:%OS%z")
}
}
}
rel
}
## Note that originally we had only resultSet both for SELECTs
## and INSERTS, ... Later on we created a base class dbResult
## for non-Select SQL and a derived class resultSet for SELECTS.
postgresqlResultInfo <- function(obj, what = "", ...) {
if(!isPostgresqlIdCurrent(obj))
stop(paste("expired", class(obj), deparse(substitute(obj))))
id <- as(obj, "integer")
info <- .Call(RS_PostgreSQL_resultSetInfo, id)
if(!missing(what))
info[what]
else
info
}
postgresqlDescribeResult <- function(obj, verbose = FALSE, ...) {
if(!isPostgresqlIdCurrent(obj)){
print(obj)
invisible(return(NULL))
}
print(obj)
cat(" Statement:", dbGetStatement(obj), "\n")
cat(" Has completed?", if(dbHasCompleted(obj)) "yes" else "no", "\n")
cat(" Affected rows:", dbGetRowsAffected(obj), "\n")
cat(" Rows fetched:", dbGetRowCount(obj), "\n")
flds <- dbColumnInfo(obj)
if(verbose && !is.null(flds)){
cat(" Fields:\n")
out <- print(dbColumnInfo(obj))
}
invisible(NULL)
}
postgresqlCloseResult <- function(res, ...) {
if(!isPostgresqlIdCurrent(res))
return(TRUE)
rsId <- as(res, "integer")
.Call(RS_PostgreSQL_closeResultSet, rsId)
}
## Use NULL, "", or 0 as row.names to prevent using any field as row.names.
postgresqlReadTable <- function(con, name, row.names = "row.names", check.names = TRUE, ...) {
out <- dbGetQuery(con, paste("SELECT * from", postgresqlTableRef(name)))
if(check.names)
names(out) <- make.names(names(out), unique = TRUE)
## should we set the row.names of the output data.frame?
nms <- names(out)
j <- switch(mode(row.names),
"character" = if(row.names=="") 0 else
match(tolower(row.names), tolower(nms),
nomatch = if(missing(row.names)) 0 else -1),
"numeric" = row.names,
"NULL" = 0,
0)
if(j==0)
return(out)
if(j<0 || j>ncol(out)){
warning("row.names not set on output data.frame (non-existing field)")
return(out)
}
rnms <- as.character(out[,j])
if(all(!duplicated(rnms))){
out <- out[,-j, drop = FALSE]
row.names(out) <- rnms
} else warning("row.names not set on output (duplicate elements in field)")
out
}
postgresqlImportFile <- function(con, name, value, field.types = NULL, overwrite = FALSE,
append = FALSE, header, row.names, nrows = 50, sep = ",",
eol="\n", skip = 0, quote = '"', ...) {
if(overwrite && append)
stop("overwrite and append cannot both be TRUE")
new.con <- con
if(dbExistsTable(con,name)){
if(overwrite){
if(!dbRemoveTable(con, name)){
warning(paste("table", name, "couldn't be overwritten"))
return(FALSE)
}
}
else if(!append){
warning(paste("table", name, "exists in database: aborting dbWriteTable"))
return(FALSE)
}
}
## compute full path name (have R expand ~, etc)
fn <- file.path(dirname(value), basename(value))
if(missing(header) || missing(row.names)){
f <- file(fn, open="r")
if(skip>0)
readLines(f, n=skip)
txtcon <- textConnection(readLines(f, n=2))
flds <- count.fields(txtcon, sep)
close(txtcon)
close(f)
nf <- length(unique(flds))
}
if(missing(header)){
header <- nf==2
}
if(missing(row.names)){
if(header)
row.names <- if(nf==2) TRUE else FALSE
else
row.names <- FALSE
}
new.table <- !dbExistsTable(con, name)
if(new.table){
## need to init table, say, with the first nrows lines
d <- read.table(fn, sep=sep, header=header, skip=skip, nrows=nrows, ...)
sql <-
postgresqlBuildTableDefinition(new.con, name, obj=d, field.types = field.types,
row.names = row.names)
rs <- try(dbSendQuery(new.con, sql))
if(inherits(rs, ErrorClass)){
warning("could not create table: aborting postgresqlImportFile")
return(FALSE)
}
else
dbClearResult(rs)
}
else if(!append){
warning(sprintf("table %s already exists -- use append=TRUE?", name))
}
fmt <- paste("COPY %s FROM '%s' ","WITH DELIMITER AS '%s' ",
if(!is.null(quote)) "CSV QUOTE AS '%s'", sep="")
if(is.null(quote))
sql <- sprintf(fmt, name,fn, sep)
else
sql <- sprintf(fmt, name,fn, sep, quote)
rs <- try(dbSendQuery(new.con, sql))
if(inherits(rs, ErrorClass)){
warning("could not load data into table")
return(FALSE)
}
dbClearResult(rs)
TRUE
}
## Create table "name" (must be an SQL identifier) and populate
## it with the values of the data.frame "value"
## TODO: This function should execute its sql as a single transaction,
## and allow converter functions.
postgresqlWriteTable <- function(con, name, value, field.types, row.names = TRUE,
overwrite = FALSE, append = FALSE, ..., allow.keywords = FALSE) {
if(overwrite && append)
stop("overwrite and append cannot both be TRUE")
if(!is.data.frame(value))
value <- as.data.frame(value)
if(row.names){
value <- cbind(row.names(value), value) ## can't use row.names= here
names(value)[1] <- "row.names"
}
if(missing(field.types) || is.null(field.types)){
## the following mapping should be coming from some kind of table
## also, need to use converter functions (for dates, etc.)
field.types <- sapply(value, dbDataType, dbObj = con)
}
i <- match("row.names", names(field.types), nomatch=0)
if(i>0) ## did we add a row.names value? If so, it's a text field.
## MODIFIED -- Sameer
field.types[i] <- dbDataType(dbObj=con, field.types[row.names])
new.con <- con
if(dbExistsTable(con,name)){
if(overwrite){
if(!dbRemoveTable(con, name)){
warning(paste("table", name, "couldn't be overwritten"))
return(FALSE)
}
}
else if(!append){
warning(paste("table",name,"exists in database: aborting assignTable"))
return(FALSE)
}
}
if(!dbExistsTable(con,name)){ ## need to re-test table for existance
## need to create a new (empty) table
sql1 <- paste("create table ", postgresqlTableRef(name), "\n(\n\t", sep="")
sql2 <- paste(paste(postgresqlQuoteId(names(field.types)), field.types), collapse=",\n\t",
sep="")
sql3 <- "\n)\n"
sql <- paste(sql1, sql2, sql3, sep="")
rs <- try(dbSendQuery(new.con, sql))
if(inherits(rs, ErrorClass)){
warning("could not create table: aborting assignTable")
return(FALSE)
} else {
dbClearResult(rs)
}
}
## convert columns we can't handle in C code
value[] <- lapply(value, function(z) {
if(is.object(z) && !is.factor(z)) as.character(z) else z
})
oldenc <- dbGetQuery(new.con, "SHOW client_encoding")
postgresqlpqExec(new.con, "SET CLIENT_ENCODING TO 'UTF8'")
sql4 <- paste("COPY", postgresqlTableRef(name),"(",paste(postgresqlQuoteId(names(value)),collapse=","),") FROM STDIN")
postgresqlpqExec(new.con, sql4)
postgresqlCopyInDataframe(new.con, value)
rs<-postgresqlgetResult(new.con)
retv <- TRUE
if (inherits(rs, ErrorClass)) {
warning("could not load data into table")
retv <- FALSE
}
dbClearResult(rs)
sql5 <- paste("SET CLIENT_ENCODING TO '", oldenc, "'", sep="")
dbGetQuery(new.con, sql5)
retv
}
postgresqlBuildTableDefinition <- function(dbObj, name, obj, field.types = NULL, row.names = TRUE, ...) {
if(!is.data.frame(obj))
obj <- as.data.frame(obj)
if(!is.null(row.names) && row.names){
obj <- cbind(row.names(obj), obj) ## can't use row.names= here
names(obj)[1] <- "row.names"
}
if(is.null(field.types)){
## the following mapping should be coming from some kind of table
## also, need to use converter functions (for dates, etc.)
field.types <- sapply(obj, dbDataType, dbObj = dbObj)
}
i <- match("row.names", names(field.types), nomatch=0)
if(i>0) ## did we add a row.names value? If so, it's a text field.
field.types[i] <- dbDataType(dbObj, field.types$row.names)
## need to create a new (empty) table
flds <- paste(postgresqlQuoteId(names(field.types)), field.types)
paste("CREATE TABLE", postgresqlTableRef(name), "\n(", paste(flds, collapse=",\n\t"), "\n)")
}
## find a suitable SQL data type for the R/S object obj
## TODO: Lots and lots!! (this is a very rough first draft)
## need to register converters, abstract out PostgreSQL and generalize
## to Oracle, Informix, etc. Perhaps this should be table-driven.
## NOTE: PostgreSQL data types differ from the SQL92 (e.g., varchar truncate
## trailing spaces).
postgresqlDataType <- function(obj, ...) {
rs.class <- data.class(obj)
if(rs.class=="numeric"){
sql.type <- if(is(obj,"integer")) "integer" else "float8"
}
else {
sql.type <- switch(rs.class,
character = "text",
logical = "bool",
factor = "text",
ordered = "text",
Date = "date",
POSIXct = "timestamp with time zone",
"text")
}
sql.type
}
postgresqlQuoteId <- function(identifiers){
ret <- paste('"', gsub('"','""',identifiers), '"', sep="")
ret
}
postgresqlTableRef <- function(identifiers){
ret <- paste('"', gsub('"','""',identifiers), '"', sep="", collapse=".")
ret
}
## the following reserved words were taken from ["RESERVED" of postgres colomn in ] Table C.1 in Appendix C
## of the PostgreSQL Manual 8.3.1.
.PostgreSQLKeywords <- c("ALL", "ANALYSE", "ANALYZE", "AND", "ANY",
"ARRAY", "AS", "ASC", "ASYMMETRIC", "AUTHORIZATION", "BETWEEN",
"BINARY", "BOTH", "CASE", "CAST", "CHECK", "COLLATE", "COLUMN",
"CONSTRAINT", "CREATE", "CROSS", "CURRENT_DATE", "CURRENT_ROLE",
"CURRENT_TIME", "CURRENT_TIMESTAMP", "CURRENT_USER", "DEFAULT",
"DEFERRABLE", "DESC", "DISTINCT", "DO", "ELSE", "END", "EXCEPT",
"FALSE", "FOR", "FOREIGN", "FREEZE", "FROM", "FULL", "GRANT", "GROUP",
"HAVING", "ILIKE", "IN", "INITIALLY", "INNER","INTERSECT", "INTO",
"IS", "ISNULL", "JOIN", "LEADING", "LEFT", "LIKE", "LIMIT",
"LOCALTIME", "LOCALTIMESTAMP", "NATURAL", "NEW", "NOT", "NULL", "OFF",
"OFFSET", "OLD", "ON", "ONLY", "OR", "ORDER", "OUTER", "OVERLAPS",
"PLACING", "PRIMARY", "REFERENCES", "RESERVED", "SELECT",
"SESSION_USER", "SIMILAR", "SOME", "SYMMETRIC", "TABLE", "THEN", "TO",
"TRAILING", "TRUE", "UNION", "UNIQUE", "USER", "USING", "VERBOSE",
"WHEN", "WHERE", "WITH" )
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