diff --git a/scripts/check-samples.py b/scripts/check-samples.py
new file mode 100644
index 0000000..1ed0eb6
--- /dev/null
+++ b/scripts/check-samples.py
@@ -0,0 +1,332 @@
+#! python
+"""Check Samples and help upgrading icat.server to 7.0
+
+This script is supposed to run various checks and maintenance tasks on
+Samples in an ICAT server.  It is mostly aimed at assisting an upgrade
+of icat.server to version 7.0 which requires the Sample.pid attribute
+to be populated with unique non-null values.
+
+The script implements the following subcommands:
+
+stats
+    Display some statistics and provide an indication whether there
+    are any obstacles for the upgrade to icat.server 7.0.
+
+lsdup
+    List all non-unique Sample.pid values along with the corresponding
+    samples.
+
+setpids
+    Populate the pid attribute for all samples having it not set.  The
+    values are of the form "<prefix>:<id>" which is guaranteed to be
+    unique unless there are any existing samples using the same
+    prefix.  These values are considered to be placeholders that may
+    be replaced by something more sensible later on.  The default
+    prefix is "_local", but this can be changed on the command line.
+
+dedup
+    Deduplicate existing pid values in samples, e.g. change them to be
+    unique.  This is done by appending a suffix: the value "<pid>"
+    will be changed to "<pid>/dedup-<nnn>" with some incremental
+    number <nnn>.
+
+For the subcommands that set new pid values (setpids and dedup), the
+script checks whether there are any existing pid values that could
+potentially conflict with the new values to be set before making any
+changes.  In this case, the change will not be applied unless forced.
+
+The script needs to be run by a user having read access to all
+samples.  While this sounds like stating the obvious, it is important
+to mention here, because obviously, the script can not point on issues
+if it is not allowed to see them.  And the script has no way to detect
+whether there are more samples than it is allowed to see.  So you
+won't get any sort of a warning if the script can't see all the
+samples.  Furthermore, for the setpids and dedup subcommands, the user
+running the scripts needs the corresponding update permissions.
+
+"""
+
+import logging
+import math
+import re
+import icat
+import icat.config
+from icat.query import Query
+
+logging.NOTICE = logging.INFO + 5
+logging.addLevelName(logging.NOTICE, "NOTICE")
+logging.basicConfig(level=logging.INFO, format="%(levelname)s: %(message)s")
+logger = logging.getLogger(__name__)
+
+# ============================= helper ===============================
+
+def searchChunkedNoSkip(client, query, chunksize=100):
+    """A variant of client.searchChunked() that does not skip.
+
+    To be used in cases where the body of the loop modifies the result
+    set in a way that the treated objects do not match the search
+    criterion any more.
+    """
+    query = query.copy()
+    query.setLimit((0, chunksize))
+    while True:
+        items = client.search(query)
+        for item in items:
+            yield item
+        if len(items) < chunksize:
+            break
+
+def get_pid_prefixes(client):
+    prefixes = set()
+    query = Query(client, "Sample", conditions={
+        "pid": "LIKE '%:%'"
+    }, attributes=["pid"], aggregate="DISTINCT")
+    for pid in client.searchChunked(query):
+        p, _ = pid.split(':', maxsplit=1)
+        prefixes.add(p)
+    return prefixes
+
+def get_samples_by_pid(client, pid):
+    query = Query(client, "Sample", conditions={
+        "pid": "= '%s'" % pid
+    }, order=["id"], includes="1")
+    return client.searchChunked(query)
+
+def get_max_sample_id(client):
+    query = Query(client, "Sample",
+                  attributes=["id"], order=[("id", "DESC")], limit=(0, 1))
+    try:
+        return client.assertedSearch(query)[0]
+    except icat.SearchAssertionError as exc:
+        if exc.num == 0:
+            return 1
+        else:
+            raise
+
+def find_potential_upgrade_conflicts(client, prefix):
+    auto_pid_re = re.compile(r"%s:\d+" % prefix)
+    query = Query(client, "Sample", conditions={
+        "pid": "LIKE '%s:%%'" % prefix
+    })
+    for sample in client.searchChunked(query):
+        pid = str(sample.pid)
+        if not auto_pid_re.fullmatch(pid):
+            continue
+        p, i = pid.split(':')
+        if int(i) != sample.id:
+            yield sample.id, pid
+
+def find_potential_dedup_conflicts(client, pid):
+    auto_pid_re = re.compile(r"%s/dedup-\d+" % pid)
+    query = Query(client, "Sample", conditions={
+        "pid": "LIKE '%s/%%'" % pid
+    })
+    for sample in client.searchChunked(query):
+        if not auto_pid_re.fullmatch(str(sample.pid)):
+            continue
+        yield sample.id, sample.pid
+
+def find_duplicate_pids(client):
+    pid_query = Query(client, "Sample", conditions={
+        "pid": "IS NOT NULL"
+    }, attributes=["pid"], order=["pid"], aggregate="DISTINCT")
+    for pid in client.searchChunked(pid_query):
+        count_query = Query(client, "Sample", conditions={
+            "pid": "= '%s'" % pid
+        }, aggregate="COUNT")
+        if client.assertedSearch(count_query)[0] == 1:
+            continue
+        yield pid
+
+def sample_attr_string(sample):
+    attrs = []
+    attrs.append("id:%d" % sample.id)
+    attrs.append("name:'%s'" % sample.name)
+    attrs.append("investigation.name:'%s'" % sample.investigation.name)
+    attrs.append("investigation.visitId:'%s'" % sample.investigation.visitId)
+    if sample.type:
+        attrs.append("type.name:'%s'" % sample.type.name)
+    return ", ".join(attrs)
+
+# ============================= stats ================================
+# The stats subcommand: provide some statistics and predict whether
+# there are any obstacles for the schema upgrade.
+
+def cmd_stats(client, conf):
+    have_warning = False
+
+    query = Query(client, "Sample", aggregate="COUNT")
+    num_samples = client.assertedSearch(query)[0]
+    logger.info("number of samples: %d", num_samples)
+
+    query = Query(client, "Sample", conditions={
+        "pid": "IS NOT NULL"
+    }, aggregate="COUNT")
+    num_samples_pid = client.assertedSearch(query)[0]
+    logger.info("number of samples having pid set: %d", num_samples_pid)
+    assert num_samples_pid <= num_samples
+
+    query = Query(client, "Sample", conditions={
+        "pid": "IS NOT NULL"
+    }, attributes=["pid"], aggregate="COUNT:DISTINCT")
+    num_pid_values = client.assertedSearch(query)[0]
+    logger.info("number of distinct pid values: %d", num_pid_values)
+    assert num_pid_values <= num_samples_pid
+    if num_pid_values < num_samples_pid:
+        logger.warning("there are duplicate pid values")
+        have_warning = True
+
+    query = Query(client, "Sample", conditions={
+        "pid": "IS NULL"
+    }, aggregate="COUNT")
+    num_samples_nopid = client.assertedSearch(query)[0]
+    logger.info("number of samples having no pid set: %d", num_samples_nopid)
+    assert num_samples_nopid <= num_samples
+    assert num_samples_pid + num_samples_nopid == num_samples
+
+    prefixes = get_pid_prefixes(client)
+    if prefixes:
+        prefix_list = ",".join(("'%s'" % p for p in sorted(prefixes)))
+        logger.info("prefixes in use in sample pids: %s", prefix_list)
+        if num_samples_nopid > 0 and '_local' in prefixes:
+            for id, pid in find_potential_upgrade_conflicts(client, '_local'):
+                logger.warning("potentially conflicting pid value '%s' "
+                               "in Sample %d", pid, id)
+                have_warning = True
+    else:
+        logger.info("no prefixes in use in sample pids")
+
+    if have_warning:
+        logger.warning("there were warnings that need to be fixed "
+                       "before upgrading to icat.server 7.0!")
+    else:
+        logger.info("no warnings, upgrading to icat.server 7.0 should succeed")
+
+def cfg_stats(subcmd):
+    help_string = "provide statistics and predict obstacles for schema upgrade"
+    sub_cfg = subcmd.add_subconfig("stats",
+                                   dict(help=help_string),
+                                   func=cmd_stats)
+
+# ============================= lsdup ================================
+# The lsdup subcommand: show duplicates, e.g. different samples having
+# the same pid value.
+
+def cmd_lsdup(client, conf):
+    num_dup_pid = 0
+    for pid in find_duplicate_pids(client):
+        num_dup_pid += 1
+        dup_list = ""
+        for sample in get_samples_by_pid(client, pid):
+            dup_list += "\n\t%s" % sample_attr_string(sample)
+        logger.warning("duplicate pid '%s': %s", pid, dup_list)
+    if num_dup_pid:
+        logger.warning("%d duplicate pids found", num_dup_pid)
+    else:
+        logger.info("no duplicate pids found")
+
+def cfg_lsdup(subcmd):
+    help_string = "show duplicates, e.g. samples having the same pid attributes"
+    sub_cfg = subcmd.add_subconfig("lsdup",
+                                   dict(help=help_string),
+                                   func=cmd_lsdup)
+
+# ============================ setpids ===============================
+# The setpids subcommand: populate the pid attribute for all samples
+# having it not set.
+
+def cmd_setpids(client, conf):
+    have_warning = False
+    for id, pid in find_potential_upgrade_conflicts(client, conf.prefix):
+        logger.warning("potentially conflicting pid value '%s' "
+                       "in Sample %d", pid, id)
+        have_warning = True
+    if have_warning:
+        if conf.force:
+            logger.warning("potential conflicts detected, "
+                           "proceeding anyway with force")
+        else:
+            logger.warning("potential conflicts detected, "
+                           "won't proceed without force")
+            return
+    num_digits = max(math.ceil(math.log10(get_max_sample_id(client)))+1, 3)
+    query = Query(client, "Sample", conditions={
+        "pid": "IS NULL"
+    }, includes="1")
+    count = 0
+    for sample in searchChunkedNoSkip(client, query):
+        sample.pid = "%s:%0*d" % (conf.prefix, num_digits, sample.id)
+        sample.update()
+        count += 1
+    logger.info("%d pid attributes set", count)
+
+def cfg_setpids(subcmd):
+    help_string = "populate the pid attribute for all samples having it not set"
+    sub_cfg = subcmd.add_subconfig("setpids",
+                                   dict(help=help_string),
+                                   func=cmd_setpids)
+    sub_cfg.add_variable('prefix', ("--prefix",),
+                         dict(help="prefix to use in the dummy pid values"),
+                         default="_local")
+    sub_cfg.add_variable('force', ("--force",),
+                         dict(help="do it even if there is the risk of "
+                              "creating new conflicts"),
+                         default=False, type=icat.config.flag)
+
+# ============================= dedup ================================
+# The dedup subcommand: deduplicate pid values.
+
+def cmd_dedup(client, conf):
+    num_dedup_pid = 0
+    for pid in list(find_duplicate_pids(client)):
+        have_warning = False
+        for id, pid2 in find_potential_dedup_conflicts(client, pid):
+            logger.warning("potentially conflicting pid value '%s' "
+                           "in Sample %d", pid2, id)
+            have_warning = True
+        if have_warning:
+            if conf.force:
+                logger.warning("potential conflicts detected, "
+                               "proceeding with dedup '%s' anyway with force",
+                               pid)
+            else:
+                logger.warning("potential conflicts detected, "
+                               "won't proceed with dedup '%s' without force",
+                               pid)
+                continue
+        count = 0
+        query = Query(client, "Sample", conditions={
+            "pid": "= '%s'" % pid
+        }, order=["id"], includes="1")
+        for sample in searchChunkedNoSkip(client, query):
+            sample.pid = "%s/dedup-%03d" % (pid, count)
+            sample.update()
+            count += 1
+        num_dedup_pid += 1
+    logger.info("%d pid values deduplicated", num_dedup_pid)
+
+def cfg_dedup(subcmd):
+    help_string = "deduplicate pid values"
+    sub_cfg = subcmd.add_subconfig("dedup",
+                                   dict(help=help_string),
+                                   func=cmd_dedup)
+    sub_cfg.add_variable('force', ("--force",),
+                         dict(help="do it even if there is the risk of "
+                              "creating new conflicts"),
+                         default=False, type=icat.config.flag)
+
+# ============================== main ================================
+
+if __name__ == '__main__':
+    logger.log(logging.NOTICE,
+               "this scripts needs to be run by a user "
+               "having read access to all samples!")
+    config = icat.config.Config(ids=False)
+    subcmd = config.add_subcommands()
+    cfg_stats(subcmd)
+    cfg_lsdup(subcmd)
+    cfg_setpids(subcmd)
+    cfg_dedup(subcmd)
+    client, conf = config.getconfig()
+    client.login(conf.auth, conf.credentials)
+    conf.subcmd.func(client, conf)
diff --git a/setup.py b/setup.py
index 7ac3f96..aaa70fc 100644
--- a/setup.py
+++ b/setup.py
@@ -18,6 +18,7 @@
     url = "https://github.com/icatproject-contrib/scripts",
     license = "Apache-2.0",
     scripts = [
+        "scripts/check-samples.py",
         "scripts/check-sizes.py",
         "scripts/test-schema-sizes-triggers.py",
         "scripts/panet.py",